Mobile App Development Vocabulary: 100 Key English Terms
Mobile development runs on English: Apple and Google write their developer documentation, review guidelines and policy emails in English, and Xcode, Android Studio and crash reporting tools use the same words. Knowing these terms helps iOS, Android and cross-platform developers read platform docs faster, understand store review feedback and talk clearly with designers, testers and product teams.
100 terms
10 topics
50 core terms
200 example sentences
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No account needed. Read the meaning, see where the term is used, then study the examples. Click any word in the lesson for help. You can also select a word and press Alt + Enter.
iOS, Android and Native Development
mobile app
noun
Meaning
A program designed to run on a smartphone or tablet, usually downloaded from an app store such as the App Store or Google Play.
Where you use it
The everyday word in job ads, meetings and product plans. In speech people simply say 'the app'; 'application' sounds more formal and is more common in documentation and official names.
Examples
Most of our customers now order through the mobile app, not the website.
We need a mobile app for both iOS and Android by the end of the year.
Usage note
'Application' also means a job application; in software it means a program. Turkish 'aplikasyon' is not used for software: say 'uygulama'.
Common phrases
build a mobile app · mobile app developer · launch a mobile app · mobile app users
Apple's operating system for the iPhone. Apps for it are built with Apple's own tools, mainly Xcode and the Swift programming language.
Where you use it
Used as a noun and before other nouns: iOS app, iOS developer, iOS version. Developers often talk about the minimum iOS version an app supports. Since 2019 the iPad's system has its own name, iPadOS, but it shares most of the same SDK.
Examples
The bug only happens on iOS 17; Android users are not affected.
We're dropping support for iOS 15 in the next release.
Usage note
Always written with a small 'i' and capital 'OS', and read letter by letter: 'eye-oh-ess'.
Common phrases
iOS app · iOS developer · minimum iOS version · support older iOS versions
Google's mobile operating system, used by many phone makers such as Samsung, Xiaomi and Google itself. Its apps are mainly written in Kotlin or Java.
Where you use it
Used like iOS: Android app, Android developer, Android version. Developers also talk about API levels (each Android version has a number, such as API 34 for Android 14) and about testing on many different devices from different manufacturers.
Examples
The layout looks fine on Pixel phones but breaks on some older Android devices.
In Turkey, our Android app has twice as many users as the iOS one.
Common phrases
Android app · Android device · Android version · API level
An app built for one specific platform with that platform's own languages and tools, such as Swift for iOS or Kotlin for Android.
Where you use it
Usually compared with cross-platform and hybrid apps. Teams discuss whether to 'go native' for better performance and full access to device features, or to share code across platforms. 'Native' is also used alone: native code, native module, native look and feel.
Examples
The banking team chose a separate native app for each platform because of the security requirements.
A native app can use new iOS features on the day they are released.
Usage note
'Native' here has nothing to do with 'native speaker'; it means 'made with the platform's own tools'.
Common phrases
build a native app · go native · native code · native performance
Software development kit: a set of tools, libraries and documentation for building apps for a platform or for adding a service, such as payments or analytics, to an app.
Where you use it
Developers speak about the iOS SDK and the Android SDK, and also about third-party SDKs they integrate, such as a maps or payment SDK. In Android projects, minSdk and targetSdk set the oldest supported and the target Android versions.
Examples
We added the payment provider's SDK, and the app size grew by 4 MB.
Google Play makes us raise the target SDK version every year.
Common phrases
integrate an SDK · third-party SDK · iOS SDK · target SDK version
A program that copies the hardware and software of a mobile device on a computer, so you can run and test an app without a real phone.
Where you use it
The word Android developers use: the Android Emulator comes with Android Studio, and you create virtual devices (AVDs) with different screen sizes and Android versions. Typical phrases: run on the emulator, launch the emulator, test on an emulator.
Examples
It works on the emulator, but it crashes on my Samsung.
Create an emulator with API 26 so we can check the oldest supported version.
Usage note
iOS developers say simulator, Android developers say emulator; in conversation many people use the two words interchangeably.
Common phrases
Android Emulator · run on the emulator · launch the emulator · test on an emulator
Apple's tool, included with Xcode, that runs iOS apps on a Mac in a window that looks like an iPhone or iPad, without imitating the real device hardware.
Where you use it
iOS developers say 'run it on the simulator' or 'in the Simulator'. Because it uses the Mac's own processor, some things behave differently from a real device, such as performance, the camera and some sensors, so final testing is done on real iPhones.
Examples
The animation is smooth on the simulator but laggy on an iPhone 11.
Can you check the new layout on the iPad simulator too?
Common phrases
iOS Simulator · run on the simulator · reset the simulator · simulator build
Apple's development environment for writing, building, testing and publishing apps for iPhone, iPad, Mac and other Apple platforms. It runs only on macOS.
Where you use it
iOS developers open a project in Xcode, run it on a simulator, archive a build and upload it to App Store Connect from there. A new Xcode version arrives with each major iOS version, and teams often have to update Xcode to use the latest SDK.
Examples
After updating Xcode, the project doesn't compile anymore.
Archive the app in Xcode and upload it to TestFlight.
Usage note
Pronounced 'ex-code'. It cannot be installed on Windows or Linux, so iOS development normally needs a Mac.
Common phrases
open in Xcode · update Xcode · Xcode project · Xcode version · archive in Xcode
Google's official development environment for Android apps, based on IntelliJ IDEA, with a code editor, the Android Emulator, profilers and build tools.
Where you use it
Android developers open, build and run projects in Android Studio, manage virtual devices, read Logcat and work with the Gradle build system. Unlike Xcode, it runs on Windows, macOS and Linux.
Examples
Open the project in Android Studio and sync Gradle first.
Android Studio's profiler shows memory going up every time we open the gallery.
Common phrases
open in Android Studio · Android Studio profiler · update Android Studio · Android Studio project
The programming language Apple introduced in 2014 for building apps on iOS and its other platforms; it has largely replaced the older Objective-C.
Where you use it
Job ads ask for Swift experience, often together with SwiftUI and UIKit. Developers talk about Swift versions, Swift packages (Swift Package Manager) and newer language features such as async/await and Swift concurrency.
Examples
We're rewriting the old Objective-C screens in Swift.
Candidates should have at least two years of Swift experience.
Common phrases
written in Swift · Swift developer · Swift package · Swift concurrency
A modern programming language created by JetBrains that Google recommends as the main language for Android development; it works alongside Java code.
Where you use it
Since 2019 Android development has been 'Kotlin-first', so most new Android code, libraries and documentation use Kotlin. Developers talk about coroutines for asynchronous work, Kotlin Multiplatform for sharing code with iOS, and migrating from Java to Kotlin.
Examples
All new Android features are written in Kotlin, but some old classes are still in Java.
We use Kotlin coroutines for all network calls.
Common phrases
written in Kotlin · Kotlin coroutines · Kotlin Multiplatform · migrate to Kotlin
Apple's declarative framework, introduced in 2019, for building user interfaces in Swift by describing what the screen should show for each state.
Where you use it
Often compared with UIKit, the older imperative framework, and many apps mix the two. Developers talk about views, modifiers, @State and Xcode previews. Job ads usually list 'SwiftUI and UIKit' together.
Examples
New screens are written in SwiftUI, but the old ones still use UIKit.
The SwiftUI preview lets the designer check every state without running the app.
Common phrases
SwiftUI view · SwiftUI and UIKit · SwiftUI preview · migrate to SwiftUI
Google's modern declarative toolkit for building Android user interfaces in Kotlin, using composable functions instead of XML layouts.
Where you use it
Usually just called Compose. It became stable in 2021 and is now Google's recommended way to build Android UI. Developers talk about composables, recomposition, state hoisting and Material 3 components.
Examples
We migrated the settings screen from XML to Jetpack Compose.
In Jetpack Compose, unnecessary recompositions can make a list stutter.
Common phrases
composable function · recomposition · Compose UI · migrate to Compose
Describes an app or framework that runs on more than one platform, usually both iOS and Android, from one shared codebase.
Where you use it
Used before nouns (cross-platform app, cross-platform framework, cross-platform development) and in discussions about cost, speed and performance. React Native and Flutter are the best-known cross-platform frameworks; Kotlin Multiplatform focuses on sharing business logic.
Examples
A cross-platform app let us ship to both stores with a team of three.
Is cross-platform development fast enough for a video editing app?
Common phrases
cross-platform app · cross-platform framework · cross-platform development · go cross-platform
A cross-platform framework created by Meta that lets developers build iOS and Android apps with JavaScript or TypeScript and React, using real native UI components.
Where you use it
Popular with teams that already know React for the web. Developers mention Expo, a toolset that makes React Native projects easier to set up and build, and native modules, which they write when they need platform features that React Native does not provide.
Examples
Our web team already knows React, so React Native was the obvious choice.
This animation is smooth in Swift but drops frames in React Native.
Common phrases
React Native app · React Native developer · built with React Native · React Native project
Google's open-source framework for building mobile, web and desktop apps from one codebase; it uses the Dart language and draws its own UI on the screen.
Where you use it
Developers talk about widgets (everything in Flutter is a widget), hot reload, packages from pub.dev and state management options such as Provider, Riverpod or Bloc. Because Flutter draws its own UI, an app looks the same on every platform unless developers adapt it.
Examples
We built the first version in Flutter and launched on both stores in three months.
An app built with web technologies such as HTML, CSS and JavaScript and wrapped in a native shell, so it can be installed from the stores and use some device features.
Where you use it
Built with tools such as Ionic, Capacitor or the older Apache Cordova; the content runs inside a web view. Often compared with native and cross-platform apps: hybrid apps reuse web code but may feel less smooth than native ones.
Examples
Our first version was a hybrid app built with Cordova, and scrolling was never smooth.
A hybrid app was enough for the internal expense tool.
A component that shows web pages inside an app without opening a separate browser, so developers can display web content within a native screen.
Where you use it
On iOS the class is WKWebView, and on Android it is WebView. Teams use web views for help pages, payment forms or entire hybrid apps. Developers talk about loading a URL in a web view, passing messages between JavaScript and native code, and web view performance.
Examples
The FAQ is just a web view that loads our help center.
The 3D Secure page opens in a web view, and the bank redirects the user back to the app.
Common phrases
load a URL in a web view · embedded web view · WKWebView · web view content
A development feature that shows code changes in the running app within a second or two, usually without losing the current screen or its state.
Where you use it
Best known from Flutter, where it is contrasted with hot restart, which resets the app's state. React Native's version is called Fast Refresh, while SwiftUI and Jetpack Compose offer live previews. Developers say a change 'didn't hot reload' when it needs a full rebuild.
Examples
With hot reload, the designer can see color changes on the phone almost immediately.
Hot reload doesn't pick up changes in the main function, so do a hot restart.
Common phrases
hot reload · hot restart · Fast Refresh · trigger a hot reload
The series of states an app moves through from launch to being closed, such as active, in the background or suspended, and the events the system sends at each change.
Where you use it
Developers handle the lifecycle to save data, pause videos or stop location updates at the right moment. On Android it is described through methods like onCreate, onResume and onPause; on iOS through app and scene states such as active, inactive and background.
Examples
The timer stops because we don't handle the app lifecycle correctly when the phone is locked.
Every new Android developer should understand the activity and app lifecycle first.
The state of an app that is still running or kept in memory but is not visible on the screen, for example after the user switches to another app.
Where you use it
Used in phrases like 'in the background', 'go to the background', 'background task' and 'background refresh'. Both iOS and Android strictly limit what an app can do in the background to save battery, so long-running work needs special APIs.
Examples
The upload stops as soon as the app goes to the background.
We refresh the news feed in the background so it's ready when users open the app.
Common phrases
in the background · go to the background · background task · background refresh · background mode
The state of an app that is open and visible on the screen, so the user can interact with it directly.
Where you use it
Common phrases: in the foreground, come to the foreground, return to the foreground. Apps often refresh data when they return to the foreground. On Android, a 'foreground service' keeps running with a visible notification, for example for music playback or navigation.
Examples
We show the in-app message only when the app is in the foreground.
When the app comes back to the foreground, refresh the user's balance.
Common phrases
in the foreground · come to the foreground · return to the foreground · foreground service
The thread on which an app draws its interface and handles user input; if slow work runs there, the app freezes and stops responding.
Where you use it
On Android also called the UI thread. Developers move network calls, database work and image processing off the main thread, while UI updates must happen on it. Android throws NetworkOnMainThreadException for network calls there, and blocking it too long causes an ANR.
Examples
The list freezes because we decode large images on the main thread.
UI updates must run on the main thread, otherwise the app may crash.
Common phrases
on the main thread · off the main thread · block the main thread · main thread checker
Launching an app when it is not already in memory, so the system has to create everything from the beginning; it is the slowest kind of app launch.
Where you use it
Compared with warm and hot starts, when the app or parts of it are still in memory. Teams measure cold start time, try to reduce the work done at launch and track it in Google Play vitals and Xcode Organizer.
Examples
Cold start takes four seconds because we load every SDK at launch.
After the fix, cold start time dropped below one second on mid-range phones.
Common phrases
cold start time · warm start · reduce cold start · app launch time
In Android, a core app component that represents one screen with a user interface and has its own lifecycle, from being created to being destroyed.
Where you use it
Developers talk about the main activity, starting an activity with an intent, lifecycle methods (onCreate, onStart, onResume, onPause, onStop, onDestroy) and the activity being recreated after rotation. Modern apps often use a single activity with many fragments or Compose screens.
Examples
The activity is recreated when the user rotates the phone, so the form data disappears.
We moved to a single-activity architecture last year.
Usage note
In everyday English 'activity' is just something you do; in Android code it is the name of a specific class.
Common phrases
main activity · start an activity · activity lifecycle · single-activity architecture
In iOS UIKit, an object that manages one screen or part of a screen: it loads the views, responds to user actions and handles events such as the screen appearing.
Where you use it
Developers push or present a view controller and override methods such as viewDidLoad and viewWillAppear. 'Massive view controller' is a well-known problem where too much code ends up in one class. In SwiftUI, views take over much of this role.
Examples
The profile view controller has grown to 2,000 lines; we need to split it.
Present the login view controller modally if the session has expired.
Common phrases
push a view controller · present a view controller · root view controller · massive view controller
One full view of an app that the user sees at a time, such as the login screen or the settings screen; apps are planned as a set of screens.
Where you use it
Used constantly in design reviews, tickets and test steps: home screen, detail screen, 'go back to the previous screen'. In UIKit code a screen is often a view controller, on Android an activity or fragment, and in SwiftUI or Compose a view or composable.
Examples
After a successful payment, the user should land on the order summary screen.
This screen has too many buttons; let's move some of them to a menu.
Common phrases
home screen · login screen · screen size · navigate to a screen · previous screen
User interface: everything on the screen that people see and touch to use an app, such as buttons, text fields, lists and menus.
Where you use it
Very common in compounds: UI design, UI component, UI test, UI thread. Often paired with UX (user experience): UI is how the app looks and is laid out, UX is how it feels to use. Mobile UI is built with UIKit, SwiftUI, Android Views or Jetpack Compose.
Examples
The new UI looks great, but the buttons are too small for older users.
Never block the UI while the app is downloading data.
Common phrases
UI design · UI component · update the UI · block the UI
To touch the screen quickly with one finger to select something, for example a button, a link or an item in a list.
Where you use it
The standard verb in mobile test steps, bug reports and UI text: tap the button, tap on the icon, double-tap to zoom. Also a noun: one tap, with a single tap. Related gestures are long press (press and hold), swipe and pinch.
Examples
Tap the Save button twice quickly and the order is created twice.
Users can share a photo with a single tap.
Usage note
In English you click with a mouse; on a touchscreen, write 'tap'. Turkish speakers often say 'click' for both.
Common phrases
tap a button · tap on the icon · double-tap · with a single tap · tap target
To move the content of a screen up, down or sideways to see more of it, usually by sliding a finger across a list or page.
Where you use it
Common in bug reports and performance talk: scroll down, scroll to the top, smooth scrolling, the list 'jumps' while scrolling. Also a noun in 'scroll position' and 'infinite scroll', where new items load as the user reaches the end.
Examples
When you scroll fast through the product list, some images load in the wrong place.
The app should keep the scroll position when the user comes back.
Common phrases
scroll down · scroll to the top · smooth scrolling · scroll position · infinite scroll
On iOS, the bar at the top of a screen that shows the title, a back button and action buttons; on Android, the name also refers to the system bar with the back and home controls.
Where you use it
iOS developers customize the navigation bar's title, color and buttons (bar button items). On Android, people talk about the system navigation bar or gesture navigation at the bottom of the screen. Often shortened to 'nav bar'.
Examples
Put the share button on the right side of the navigation bar.
On some Android phones, the navigation bar covers the button at the bottom.
Usage note
Material Design 3 also uses 'navigation bar' for the bottom bar with the app's main sections, which iOS calls a tab bar. Check which one people mean.
Common phrases
navigation bar title · nav bar · hide the navigation bar · back button in the navigation bar
A bar, usually at the bottom of the screen, with icons that let users switch between the main sections of an app, such as Home, Search and Profile.
Where you use it
The iOS name for this pattern; Android designers say bottom navigation or, in Material 3, navigation bar. Teams discuss which tabs to show, the selected tab, badges on tab icons, and whether to hide the tab bar on detail screens.
Examples
We added a fifth item to the tab bar for the new rewards section.
Tapping the selected tab in the tab bar should scroll the list back to the top.
Common phrases
tab bar item · hide the tab bar · bottom tab bar · selected tab
To move a finger quickly across the screen in one direction, for example to see the next photo, delete an item in a list or go back.
Where you use it
Common in UI specs and test steps: swipe left, swipe right, swipe up, swipe to delete, swipe back. Also a noun (a swipe gesture). A swipe is short and fast; scroll describes moving through content, and drag means moving something while keeping the finger down.
Examples
Swipe left on a message to archive it.
Users swipe back by mistake while drawing their signature.
Common phrases
swipe left · swipe to delete · swipe back · swipe gesture · swipe up
The first screen people see while an app starts, usually showing the logo on a plain background until the main content is ready.
Where you use it
Apple calls it the launch screen and wants it to look like the app's first screen rather than an advert. Android 12 introduced the SplashScreen API, which gives every app a standard splash with its icon. Teams keep it short, because users feel a long splash as slowness.
Examples
The splash screen stays on for five seconds on older phones; that's far too long.
Marketing wants an animated logo on the splash screen.
Common phrases
splash screen animation · show a splash screen · launch screen · splash screen duration
The first screens a new user goes through after installing an app, which explain the main features, ask for permissions or help set up an account.
Where you use it
Product and design teams talk about the onboarding flow, onboarding screens and how many users complete or skip onboarding. They measure where users drop off and often try to make it shorter. In HR the same word means introducing new employees to a company.
Examples
Almost 40% of new users quit during onboarding, so we cut it from five screens to two.
Let's ask for notification permission at the end of onboarding, not on the first screen.
A display setting that shows light text on a dark background across the system and in apps that support it, often chosen for use at night.
Where you use it
Both iOS and Android have offered a system-wide dark mode since 2019. Developers support dark mode by using semantic colors that change automatically, and testers check every screen in both light and dark mode. Android documentation often says 'dark theme'.
Examples
In dark mode, the logo almost disappears against the background.
Does the new design support dark mode?
Common phrases
support dark mode · switch to dark mode · light and dark mode · dark mode colors
A small view from an app that shows live information on the home screen or lock screen, such as the weather or the next meeting, without opening the app.
Where you use it
On iOS, widgets are built with WidgetKit; on Android they are app widgets, now often built with Jetpack Glance. Users add a widget to the home screen and choose its size. In Flutter the word means any UI building block, so context matters.
Examples
Users can now add a widget that shows their daily step count.
The widget shows yesterday's balance because it doesn't refresh often enough.
Usage note
In Flutter, 'widget' means every piece of the UI, from a button to a whole screen, not a home screen widget.
Common phrases
home screen widget · add a widget · lock screen widget · widget refresh
A panel that slides up from the bottom of the screen to show extra options or content, while part of the screen behind it often stays visible.
Where you use it
A Material Design term; on iOS the same pattern is called a sheet, which can stop at different heights called detents. Users drag a bottom sheet up or swipe it down to dismiss it. It can be modal, blocking the screen behind, or persistent.
Examples
Show the filter options in a bottom sheet instead of a new screen.
The bottom sheet covers the map's zoom buttons.
Common phrases
modal bottom sheet · dismiss the bottom sheet · expand the bottom sheet · bottom sheet handle
A screen or window shown on top of the current one that users must deal with, by finishing a task or closing it, before they can return to what they were doing.
Where you use it
Used as a noun (open a modal) and an adjective (a modal screen, present modally). On iOS, a view controller can be presented modally as a full-screen cover or a sheet. Designers use modals for focused tasks such as writing a message or confirming a payment.
Examples
Closing the modal should keep what the user has typed so far.
Present the payment confirmation as a modal, not as a pushed screen.
Common phrases
open a modal · close the modal · present modally · full-screen modal
A gesture in which the user drags the top of a list downward and releases it to load the newest content, while a small spinner shows that it is loading.
Where you use it
Common in feeds, inboxes and order lists. Written with hyphens before a noun (a pull-to-refresh gesture). On iOS it is built with UIRefreshControl or SwiftUI's refreshable, and on Android with SwipeRefreshLayout or Compose's pull-to-refresh components.
Examples
Pull to refresh on the orders screen doesn't show the new order until you restart the app.
Users expect pull-to-refresh on every list.
Common phrases
pull-to-refresh gesture · refresh indicator · add pull to refresh · refresh the list
The part of the screen that is not covered by the notch, camera cutout, status bar or home indicator, where important content and buttons can be placed safely.
Where you use it
An Apple term (safe area insets, safe area layout guide); Android developers talk about window insets and display cutouts instead. Bugs where a button sits under the home indicator are often described as 'not respecting the safe area'.
Examples
The Pay button is under the home indicator; the layout ignores the safe area.
The background image can go edge to edge, but the text must stay inside the safe area.
Common phrases
safe area insets · respect the safe area · ignore the safe area · window insets
The way a device is held and the screen is shown: portrait (upright) or landscape (sideways); an app can support one or both.
Where you use it
Teams decide whether to lock the orientation or support rotation. On Android, an orientation change is a configuration change that recreates the activity by default, which can lose state if not handled. Tablets and foldable phones make orientation support more important.
Examples
The app is locked to portrait orientation, except for the video player.
The form resets after an orientation change on Android.
How many pixels a screen has in a given physical area, measured in dots per inch (dpi); high-density screens need larger image files to look sharp.
Where you use it
To keep sizes consistent, Android uses density-independent pixels (dp) and density buckets such as hdpi, xhdpi and xxhdpi, while iOS uses points and @2x and @3x image assets. Designers hand off sizes in dp or pt, not in raw pixels.
Examples
The icons look blurry because we only exported them for one screen density.
Let's use vector images so we don't need a separate file for every screen density.
Common phrases
screen density · density-independent pixels · high-density screen · @2x and @3x assets
Application programming interface: a defined way for programs to talk to each other; in mobile work, usually the server endpoints an app calls to get and send data.
Where you use it
Mobile developers call an API, wait for the API response and handle API errors. The word also covers platform features that apps use, such as the camera API or the location API on iOS and Android.
Examples
The app is fast, but the API takes four seconds to return the search results.
The back-end team changed the API without telling us, so the old app version broke.
Common phrases
call an API · API response · API endpoint · API key · REST API
A way of working in which an app stays usable without an internet connection, showing saved data and sending changes later when the connection returns.
Where you use it
Common in requirements and planning: support offline mode, work offline, offline-first. An offline-first app saves data on the device first and syncs with the server later. Testers often check it by turning on airplane mode.
Examples
Field workers need offline mode because there is no signal on most building sites.
In offline mode, the app shows the last saved prices with a small warning.
Common phrases
support offline mode · work offline · offline-first · go offline
Space on the device itself where an app saves data, such as settings, files or a database, so it is available without contacting a server.
Where you use it
A general term for options such as UserDefaults on iOS, SharedPreferences or DataStore on Android, plain files and databases like SQLite. Teams decide what to keep in local storage and what must stay on the server. Sensitive data such as tokens is usually kept in secure storage like the keychain.
Examples
We keep the user's draft in local storage so nothing is lost if the app crashes.
Clearing local storage logs the user out and resets all settings.
Usage note
In web development, localStorage (one word) is a specific browser API; in mobile development 'local storage' is just a general description.
Common phrases
save to local storage · read from local storage · clear local storage · store data locally
To make the data on the device and on the server the same by sending local changes and downloading new ones; short for synchronize.
Where you use it
Also a noun: background sync, a sync conflict, the last sync time. Offline-first apps must decide what happens when the same item was changed on two devices, which is called conflict resolution.
Examples
Notes created offline sync automatically when the phone is back online.
Show the last sync time at the bottom of the screen.
Usage note
Pronounced like 'sink'. The spelling 'synch' also exists but is rare.
Common phrases
sync data · background sync · sync conflict · last sync time · sync with the server
A temporary store of data, such as images or API responses, kept on the device so the app can show it again quickly without downloading it.
Where you use it
Used as a noun and a verb: cache images, clear the cache, an image cache, a stale cache. The system may delete cached files when storage runs low, so a cache holds only data that can be downloaded again.
Examples
Product images are cached, so the list loads instantly the second time.
If you still see the old prices, clear the cache in the app settings.
Usage note
Pronounced like 'cash', not 'catch' or 'ka-shay'.
Common phrases
clear the cache · image cache · cache data · stale cache · cache size
A small, fast database engine stored in a single file, built into both iOS and Android and widely used to save structured data on the device.
Where you use it
Developers rarely use it directly: on Android, the Room library sits on top of SQLite, and on iOS, Core Data and SwiftData often use it as their store. Teams talk about database migrations when the data structure changes between app versions.
Examples
We store the product catalog in SQLite so search works offline.
The update crashed for some users because the SQLite migration failed.
Common phrases
SQLite database · SQLite migration · Room database · Core Data store
A message an app sends over the internet to a server, for example to load a list or save a form, together with the response it waits for.
Where you use it
Developers make, cancel and retry network requests, set timeouts and show loading states. On iOS they usually use URLSession, on Android libraries such as Retrofit and OkHttp. iOS blocks plain HTTP by default through App Transport Security, so requests normally use HTTPS.
Examples
The home screen makes twelve network requests at launch; let's combine some of them.
Retry the network request when the connection comes back.
Common phrases
make a network request · cancel a network request · retry the request · request timeout
To save data so that it stays on the device after the app is closed or the phone restarts, for example in a database, a file or the settings.
Where you use it
A technical word in code reviews and design discussions: persist the cart, persisted state, data persistence, a persistence layer. Common tools include Core Data, SwiftData, Room, DataStore and UserDefaults. In everyday English it means to continue, as in 'the problem persists'.
Examples
We persist the shopping cart, so it's still there after the app restarts.
Should we persist the filter settings or reset them every time?
Common phrases
persist data · persisted state · data persistence · persistence layer
A short message sent from a server to a user's device that appears on the screen even when the app is not open, for example about a new message or a delivery.
Where you use it
Used by developers, product managers and marketers. You send, receive, schedule and tap on push notifications; people often shorten it to 'push' (send a push). On iOS they go through Apple's APNs, and on Android usually through Firebase Cloud Messaging (FCM).
Examples
Users who turn on push notifications come back to the app much more often.
Tapping the push notification should open the order details, not the home screen.
Common phrases
send a push notification · receive push notifications · turn on push notifications · push notification permission
A link that opens a specific screen inside an app, such as a product page or an order, instead of just starting the app on its home screen.
Where you use it
Used with push notifications, emails, ads and QR codes. iOS Universal Links and Android App Links use normal web addresses; older custom URL schemes such as myapp:// are also common. A deferred deep link still works when the user has to install the app first.
Examples
The deep link in the email opens the app but lands on the home screen instead of the campaign.
Every push notification should include a deep link to the right screen.
Common phrases
open a deep link · handle deep links · deferred deep link · deep link URL
A notification that the app schedules on the device itself, for example a reminder at 9 a.m., without needing a server to send it.
Where you use it
Used for reminders, alarms, timers and calendar events. Developers schedule, cancel and update local notifications, and they still need the user's notification permission. Compared with push notifications, which come from a server.
Examples
The medicine reminder is a local notification, so it works even without internet.
Cancel the local notification if the user completes the task early.
Common phrases
schedule a local notification · cancel a local notification · repeating notification · notification trigger
Apple Push Notification service: Apple's system that delivers push notifications from a server to iPhones, iPads and other Apple devices.
Where you use it
Every push notification to an Apple device goes through APNs, even when a service such as FCM sits in between. Servers connect with an authentication key (.p8 file) or a certificate, and there are separate sandbox and production environments.
Examples
Notifications work in debug builds but not in TestFlight; are we using the production APNs environment?
Upload the APNs key to Firebase, or iOS users won't get any notifications.
Usage note
Written with a small 's' (APNs) because the 's' stands for 'service'.
Firebase Cloud Messaging: Google's free service for sending push notifications and data messages to Android, iOS and web apps.
Where you use it
The standard way to send push notifications on Android, and widely used for iOS too, where it forwards messages through APNs. Developers get an FCM registration token for each device and send messages with the HTTP v1 API or the Firebase console. It replaced the older Google Cloud Messaging (GCM).
Examples
We send all marketing pushes through FCM, for both Android and iOS.
The FCM token changes after the user reinstalls the app.
Common phrases
FCM token · send via FCM · FCM data message · Firebase console
A unique string that identifies one installation of an app on one device; the server needs it to send push notifications to that device.
Where you use it
The app registers for notifications, receives the device token (on Android, the FCM registration token) and sends it to the back end. Tokens can change, so apps send the new one when it is refreshed, and servers delete tokens that are no longer valid.
Examples
The user isn't getting notifications because we never saved their device token.
Send the device token to the server again after every login.
Common phrases
register a device token · refresh the token · invalid token · registration token
A small number or dot shown on an app icon or a tab, usually in red, that tells users how many unread items or new notifications are waiting.
Where you use it
Developers set, update and clear the badge count, on iOS often from the push notification payload. On Android, notification dots on the icon depend on the launcher. Wrong badge counts that never clear are a common user complaint.
Examples
The badge still shows 3 even after I read all my messages.
Clear the badge when the user opens the notifications screen.
To choose actively to take part in something, such as receiving notifications or sharing data; the opposite is to opt out.
Where you use it
Used as a phrasal verb (opt in to notifications) and, with a hyphen, as a noun or adjective: the opt-in rate, an opt-in prompt. iOS and, since Android 13, Android need the user's permission for notifications, so teams track how many users opt in.
Examples
Only 45% of our iOS users opt in to push notifications.
Our opt-in rate went up after we explained what the notifications are for.
Common phrases
opt in to notifications · opt-in rate · opt-in prompt · opt out
Apple's official store where users find, buy and download apps for the iPhone, iPad and other Apple devices.
Where you use it
Developers submit to, publish on and sometimes get featured on the App Store. Builds, store pages, prices and reviews are managed in App Store Connect, and publishing requires a paid Apple Developer Program membership. Written with capitals as a name; lowercase 'app store' means any app marketplace.
Examples
The update went live on the App Store this morning.
We need new App Store screenshots for the redesign.
Common phrases
submit to the App Store · publish on the App Store · App Store Connect · get featured on the App Store
Google's official store for Android apps and games, where developers publish their apps and users download and update them.
Where you use it
Developers manage releases, testing tracks, store listings and policy issues in the Google Play Console. Users often call it the Play Store. New apps are uploaded as Android App Bundles (AAB) rather than APK files.
Examples
Google Play approved the update in a few hours.
Check the Google Play Console; we got a policy warning about our privacy policy link.
Common phrases
publish on Google Play · Google Play Console · Google Play policy · Play Store listing
The check that Apple or Google does on an app or update before it appears in their store, to make sure it follows their rules and works properly.
Where you use it
Teams say a build is 'in review', 'waiting for review', has 'passed review' or 'failed review'. Apple's process is called App Review and follows the App Review Guidelines; a review often takes a day or two but can take longer, so release plans leave time for it.
Examples
The new version has been waiting for app review since Friday.
We failed app review because the demo account didn't work.
Usage note
'App review' can also mean a user's rating and comment on the store page; the context shows which meaning is intended.
Common phrases
submit for review · in review · pass app review · fail app review · App Review Guidelines
A compiled, installable version of an app produced from the source code, for example an .ipa file for iOS or an .aab or .apk file for Android.
Where you use it
Used as a noun and a verb: make a build, upload a build, a debug build, a release build, a TestFlight build. Each build has a build number, and teams often ask 'Which build are you on?' when checking a bug.
Examples
I uploaded a new build to TestFlight with the login fix.
The bug is in the release build only; the debug build works fine.
Common phrases
upload a build · release build · debug build · build number · nightly build
A version of an app made available to users, or the act of making it available; as a verb, to publish a new version in the store.
Where you use it
Teams plan releases, cut a release branch, write release notes and follow a release schedule, for example every two weeks. In the stores, release notes appear under 'What's New'. A release can be phased or staged so that only some users get the update at first.
Examples
We release a new version every second Thursday.
Let's leave the redesign out of this release and ship it next month.
Common phrases
release notes · release a new version · release cycle · release candidate · hotfix release
Testing a nearly finished version of an app with a group of real users before the public release, to find bugs and collect feedback.
Where you use it
iOS teams run beta testing through TestFlight, and Android teams use Google Play's internal, closed and open testing tracks or tools such as Firebase App Distribution. People join a beta, become beta testers and send beta feedback.
Examples
Beta testing with 200 users found three crashes we never saw in the office.
Open beta testing starts on Monday for Android users.
Common phrases
join the beta · beta tester · open beta · closed beta · beta feedback
The small image that represents an app on the home screen, in the store and in the settings; it is often the first thing users notice.
Where you use it
Designers deliver the app icon in several sizes, including 1024 × 1024 pixels for the App Store and 512 × 512 for Google Play. Android uses adaptive icons that can be shown in different shapes, and some apps offer alternate icons that users can choose.
Examples
The new app icon looks blurry on some Android launchers.
We're testing two app icons to see which one gets more downloads.
To refuse to accept an app or update into the store because it breaks a store rule or does not work properly during review.
Where you use it
Usually passive: the app was rejected, the build got rejected. Apple gives the reason with a guideline number; common causes are a crash during review, no way to delete an account, or unclear permission texts. Developers fix the issue and resubmit, or reply and appeal.
Examples
Apple rejected our update because the reviewer couldn't log in with the demo account.
If the build is rejected again, we'll miss the campaign date.
Common phrases
get rejected · rejected by Apple · rejection reason · resubmit after rejection
Apple's service for sending beta builds of iOS apps to testers, who install them with the TestFlight app before the version is released on the App Store.
Where you use it
Teams upload a build to TestFlight, add internal testers from their team and invite external testers by email or a public link. Builds for external testers go through a short beta review, and each build expires after 90 days.
Examples
The new build is on TestFlight; please check the payment flow today.
We invited the client to TestFlight so they can try the app before launch.
Common phrases
upload to TestFlight · TestFlight build · TestFlight invite · external testers · public link
The page for an app in an app store, with its name, icon, description, screenshots, ratings and other information that helps users decide to download it.
Where you use it
'Store listing' is Google Play's term; Apple calls it the product page. Teams update the listing text, screenshots and preview videos, translate the listing for different countries and test different versions of it to get more installs.
Examples
Marketing rewrote the store listing and added Turkish screenshots.
The store listing still mentions a feature we removed last year.
Common phrases
update the store listing · store listing experiment · localized store listing · product page
The number that identifies a release of an app for users, such as 3.2.1, shown in the store and usually in the app's settings.
Where you use it
Each platform also has a separate build number: on iOS, version (CFBundleShortVersionString) and build (CFBundleVersion); on Android, versionName and versionCode, a whole number that must increase with each upload. Many teams use semantic versioning: major.minor.patch.
Examples
Please include the version number and your phone model in every bug report.
We bumped the version number to 4.0 because of the redesign.
Common phrases
bump the version number · version and build number · minimum version · semantic versioning
Adding a digital signature to an app with a certificate, which proves who made it and shows that it has not been changed since it was built.
Where you use it
Required on both platforms. On iOS it involves certificates, provisioning profiles and Xcode's signing settings, and it is a well-known source of build errors. On Android, apps are signed with a key from a keystore; with Play App Signing, Google keeps the final app signing key.
Examples
The CI build fails at the code signing step because the certificate has expired.
Automatic code signing in Xcode solved most of our profile problems.
An Apple file that connects an app ID, signing certificates and, for testing, specific devices, so that a signed iOS app is allowed to run or be distributed.
Where you use it
There are development, ad hoc, App Store and enterprise profiles. Developers create, download and renew them in the Apple Developer portal, or let Xcode manage them automatically. Errors such as 'no matching provisioning profile' are a common topic in team chats.
Examples
Add the tester's iPhone to the provisioning profile, or the ad hoc build won't install.
The provisioning profile expired, so the company's internal app stopped opening.
Common phrases
renew a provisioning profile · ad hoc provisioning profile · development profile · no matching provisioning profile
A unique identifier for an app, usually written in reverse domain style such as com.company.appname, which the system and the store use to recognize it.
Where you use it
The iOS term; Android calls it the application ID or package name. It is set at the start of a project and cannot be changed once the app is published, so teams choose it carefully. Test and production versions often use separate IDs.
Examples
Use a different bundle ID for the staging app so testers can install both versions.
The push certificate was created for the wrong bundle ID.
Common phrases
bundle ID · package name · application ID · register a bundle ID
Releasing an update to a small percentage of users first and increasing it step by step, so problems can be found before everyone gets the new version.
Where you use it
Google Play's term: you start a staged rollout at, for example, 5%, then increase, halt or complete it. Apple offers a similar 'phased release' that spreads automatic updates over seven days. Teams watch crash rates closely during a rollout.
Examples
We paused the staged rollout at 10% because crashes doubled on Android 13.
If the numbers look good tomorrow, increase the staged rollout to 50%.
Common phrases
start a staged rollout · halt the rollout · increase the rollout · phased release
A screen or rule that blocks an old version of an app and makes users install the latest one before they can continue using it.
Where you use it
Also called a forced or mandatory update. Teams set a minimum supported version on the server and use it when an old version has a serious bug or no longer works with the API. On Android, Google Play's In-App Updates API offers an 'immediate' update flow for this.
Examples
Version 2.3 has a payment bug, so we're adding a force update for everyone below 2.4.
Users hate seeing a force update screen when they're in a hurry.
Common phrases
force update · minimum supported version · mandatory update · force users to update
App Store Optimization: improving an app's store page, such as its title, keywords, screenshots and ratings, so it ranks higher in search and gets more downloads.
Where you use it
Often described as 'SEO for apps', and it applies to both the App Store and Google Play. ASO specialists work on keywords, localized listings and A/B tests of icons and screenshots, and follow keyword rankings and conversion rates.
Examples
After the ASO work, we rank in the top five for 'budget planner' in Turkey.
Our ASO agency suggested changing the subtitle and the first two screenshots.
Something a user buys inside an app, such as extra features, game coins or a subscription, paid through the App Store or Google Play.
Where you use it
Often shortened to IAP. Types include consumables (used up, like coins), non-consumables (bought once, like removing ads) and subscriptions. Developers use StoreKit on iOS and the Google Play Billing Library on Android. The stores take a commission, and rules on outside payment options differ by country.
Examples
Most of our revenue comes from in-app purchases, not from ads.
Restoring an in-app purchase on a new phone doesn't work on Android.
Common phrases
make an in-app purchase · offer in-app purchases · restore purchases · consumable in-app purchase
A purchase that gives users access to content or features for a period, such as a month or a year, and renews automatically until they cancel it.
Where you use it
Teams talk about monthly and annual plans, renewals, cancellations, churn and subscription revenue. In the stores these are auto-renewable subscriptions, and users manage or cancel them in their App Store or Google Play account settings, not inside the app.
Examples
Annual subscriptions now make up 60% of our revenue.
Users keep asking support how to cancel their subscription.
Common phrases
monthly subscription · annual subscription · cancel a subscription · renew a subscription · subscription plan
A period, such as 7 or 14 days, during which users can try paid features for free before the subscription starts charging them.
Where you use it
Users start a free trial, and it converts to a paid subscription unless they cancel in time. Apple treats it as a type of introductory offer, and Google Play as a free trial offer on a subscription; teams track the trial-to-paid conversion rate closely.
Examples
We changed the free trial from three days to seven, and conversions went up.
The paywall should say clearly when the free trial ends.
A screen that blocks premium content or features and shows the paid options, such as subscription plans, that users must choose to continue.
Where you use it
Product teams design, test and optimize paywalls, and talk about soft paywalls, which can be closed, and hard paywalls, which cannot. Store rules expect the paywall to show prices and renewal terms clearly.
Examples
We moved the paywall to the end of onboarding, and trial starts doubled.
Apple asked us to show the full yearly price on the paywall.
Common phrases
show a paywall · hard paywall · soft paywall · paywall test
A business model in which the basic app is free and users pay for extra features, more content or the removal of ads.
Where you use it
A blend of 'free' and 'premium'. Used as a noun and an adjective: a freemium model, a freemium app. Teams debate which features stay free and which go behind the paywall, and measure how many free users become paying users.
Examples
We switched from a paid app to a freemium model, and downloads grew five times.
On our freemium plan, users can save up to three projects for free.
Common phrases
freemium model · freemium app · free tier · premium features
Checking with Apple or Google that a purchase made in the app is real and still valid before giving the user the paid content or features.
Where you use it
Usually done on the server to prevent fraud. With StoreKit 2, Apple provides signed transactions and the App Store Server API; on Android, the server verifies the purchase token with the Google Play Developer API. Many teams use services such as RevenueCat for this.
Examples
Without receipt validation, people were unlocking premium with a modified app.
Receipt validation fails in the sandbox because the server uses the production URL.
Usage note
Apple's old receipt file is being replaced by signed transactions in StoreKit 2, but many people still say 'receipt validation' for both.
Common phrases
server-side receipt validation · validate a receipt · purchase token · App Store Server API
A sudden failure that makes an app close unexpectedly, usually because of an error in the code that the app could not handle.
Where you use it
Used as a noun and a verb: the app crashes on launch, a crash on Android 12, fix a crash. Teams track crashes with tools such as Firebase Crashlytics or Sentry, and the most frequent crashes are often the first items in a bug-fix release.
Examples
The app crashes when you rotate the phone on the payment screen.
This crash affects only users with very old Samsung devices.
Usage note
An app that stops responding but does not close is said to 'freeze' or 'hang'; on Android this is called an ANR.
Common phrases
crash on launch · fix a crash · crash rate · reproduce a crash
A record created when an app crashes, showing the error, the stack trace, the device, the OS version and other details that help developers find the cause.
Where you use it
Developers read, symbolicate and group crash reports in tools such as Firebase Crashlytics, Sentry, Xcode Organizer and Google Play vitals. To make the reports readable, iOS teams upload dSYM files and Android teams upload R8 or ProGuard mapping files.
Examples
The crash report shows a null value on the checkout screen.
We get hundreds of crash reports from just one device model.
Common phrases
read a crash report · crash reporting tool · symbolicate a crash report · send crash reports
To find and fix the cause of a bug, for example by running the app step by step, checking logs or stopping the code at a breakpoint.
Where you use it
Also used as an adjective: debug build, debug mode, debug menu. Mobile developers debug on the simulator, on the emulator or on a real device connected by cable or Wi-Fi, using the Xcode and Android Studio debuggers and logs such as Logcat.
Examples
I spent the whole morning debugging a crash that only happens on real devices.
Can you debug it on your phone? I can't reproduce it on the emulator.
Common phrases
debug a crash · debug on a real device · debug build · debug mode · debugging session
Data about how people use an app, such as which screens they open and where they leave, collected as events to understand behavior and measure features.
Where you use it
Teams add analytics events, check analytics dashboards and talk about daily active users (DAU), retention and funnels. Common tools include Firebase Analytics, Amplitude and Mixpanel. Collecting analytics may require user consent and must be declared in the stores' privacy forms.
Examples
According to our analytics, most users never open the settings screen.
A list of the function calls that were active when an error or crash happened, which shows developers exactly where in the code it occurred.
Where you use it
Developers read, paste and share stack traces in tickets and chat. Release builds produce memory addresses or shortened names, so iOS stack traces must be symbolicated with dSYM files and Android ones deobfuscated with mapping files.
Examples
Can you paste the full stack trace into the ticket?
The stack trace points to the image loader, not to our code.
Common phrases
read a stack trace · full stack trace · symbolicated stack trace · paste the stack trace
A bug in which an app keeps memory it no longer needs, so memory use grows over time until the app slows down or the system closes it.
Where you use it
In Swift, a common cause is a retain cycle, where two objects hold strong references to each other; on Android, holding a reference to an Activity after it is destroyed. Developers find leaks with Xcode Instruments, the Android Studio profiler and LeakCanary.
Examples
There's a memory leak in the chat screen; memory goes up every time you open it.
LeakCanary found a memory leak in the old video player.
The percentage of users or sessions that did not experience a crash in a given period; a key measure of an app's stability.
Where you use it
Crash reporting tools show crash-free users and crash-free sessions. Mature apps often aim for 99.5% or higher, and teams compare the rate between releases when deciding whether to continue a staged rollout.
Examples
Our crash-free rate dropped to 98.7% after the last update.
We won't go beyond 20% rollout until the crash-free rate is back above 99.5%.
Usage note
English uses a decimal point (99.5%), while Turkish uses a comma (%99,5) and puts the percent sign first.
The wide variety of devices, screen sizes, hardware and operating system versions an app must work on, which makes testing harder, especially on Android.
Where you use it
Android developers often mention fragmentation to explain why a bug appears only on one manufacturer's phones. Teams handle it with device labs, cloud testing services such as Firebase Test Lab, and analytics that show which devices their users actually have.
Examples
Device fragmentation means we can't test on every phone, so we focus on the top 20 models.
Device fragmentation is the main reason our Android QA takes longer than iOS.
Common phrases
device fragmentation · Android fragmentation · OS fragmentation · deal with fragmentation
An automated test that uses the app the way a person would, tapping buttons, typing text and checking what appears on the screen.
Where you use it
iOS teams write UI tests with XCUITest, and Android teams use Espresso or Compose testing tools; cross-platform options include Appium and Maestro. UI tests are slower and break more easily than unit tests, so teams usually keep them for the most important flows.
Examples
The UI test for sign-up fails randomly on CI; I think it's a timing problem.
We have UI tests for login, search and checkout.
Common phrases
write a UI test · UI test fails · flaky UI test · run UI tests on CI
Faster than normal battery use caused by an app, for example through constant location tracking, frequent network calls or work that keeps running in the background.
Where you use it
Users complain about battery drain in store reviews, and both platforms show which apps use the most battery. Android's Doze mode and the background limits on iOS exist largely to reduce it. Developers check energy use with Xcode's tools and the Android Studio profiler.
Examples
Several reviews mention battery drain since we added live location sharing.
The battery drain comes from a timer that keeps running after the user leaves the screen.
Common phrases
battery drain · drain the battery · battery usage · energy impact
How much space an app needs, both as a download from the store and after installation on the device, including its code, images and libraries.
Where you use it
Teams track download size and install size, and reduce app size by removing unused libraries, compressing images and using platform features such as app thinning on iOS and Android App Bundles, which deliver only the parts each device needs.
Examples
The app size went from 60 MB to 95 MB after we added the video SDK.
Reducing app size matters in markets where many users have little free storage.
Application Not Responding: an Android error shown when an app's main thread is blocked for too long, for example about five seconds without responding to a touch.
Where you use it
Users see a dialog that lets them wait or close the app. Teams follow the ANR rate in Google Play vitals, because a high rate can reduce an app's visibility in the store. The usual fix is to move slow work off the main thread.
Examples
We get ANRs on cheap phones when the app parses a big JSON file at startup.
Our ANR rate in Play vitals is above the bad behavior threshold.
Usage note
iOS has no ANR dialog; iOS developers talk about 'hangs', which Xcode Organizer reports separately.
Common phrases
ANR rate · get an ANR · ANR dialog · Android vitals
The user's approval that an app needs before it can use sensitive features or data, such as the camera, location, contacts or notifications.
Where you use it
An app requests or asks for a permission, and the user grants or denies it. Both platforms ask at runtime, when the feature is first needed; iOS also requires a short text explaining why the app needs it. The timing and wording of the request affect how many users say yes.
Examples
If the user denies camera permission, show a button that opens the Settings app.
We ask for location permission only when the user opens the map.
A public document that explains what personal data an app collects, why it collects it, who it is shared with and how users can control it.
Where you use it
Both the App Store and Google Play require a privacy policy link. Developers also fill in privacy forms in the stores, called App Privacy details (privacy nutrition labels) on Apple and the Data safety section on Google Play, and these should match the policy.
Examples
Google Play rejected the update because the privacy policy link was broken.
Legal needs to update the privacy policy before we add the new analytics SDK.
Common phrases
privacy policy link · update the privacy policy · privacy policy URL · Data safety section
Apple's encrypted storage for small secrets such as passwords, tokens and keys, protected by the system and kept separate from normal app data.
Where you use it
iOS developers save access tokens to the keychain rather than UserDefaults. Keychain items can survive app deletion and can be shared between apps from the same developer team. The closest Android counterpart is the Android Keystore system, which protects cryptographic keys.
Examples
Store the refresh token in the keychain, not in UserDefaults.
Users stay logged in after reinstalling because the token is still in the keychain.
Common phrases
save to the keychain · keychain item · keychain access · Android Keystore
Confirming a user's identity with a physical feature, such as a fingerprint or a face scan, instead of or in addition to a password or PIN.
Where you use it
On iOS this means Face ID and Touch ID through the LocalAuthentication framework; on Android, BiometricPrompt. Banking and health apps use it to unlock the app or approve payments. The app never receives the fingerprint or face data, only a success or failure result.
Examples
Users can turn on biometric authentication to log in with Face ID.
If biometric authentication fails three times, fall back to the PIN.
Common phrases
biometric login · Face ID · Touch ID · fall back to a passcode
Apple's privacy framework, introduced in iOS 14.5, that requires apps to ask users for permission before tracking them across other companies' apps and websites.
Where you use it
Usually shortened to ATT. Apps show the system prompt asking to 'track your activity', and only if the user allows it can they read the device's advertising identifier (IDFA). Marketing teams talk about ATT opt-in rates and their effect on measuring ad campaigns.
Examples
Since App Tracking Transparency, we can't match most iOS installs to our ad campaigns.
We show a short explanation screen before the App Tracking Transparency prompt.
Common phrases
ATT prompt · ATT opt-in rate · IDFA · allow tracking
Removing the software limits Apple puts on an iPhone so it can run unapproved apps and changes; on Android, getting similar full access is called rooting.
Where you use it
Used as a noun, as a verb (jailbreak a phone) and in 'jailbroken device'. Banking, payment and streaming apps often detect jailbroken or rooted devices and limit some features, because the usual security protections may not work as expected on them.
Examples
The bank's security team wants to block login on devices with a jailbreak.
Our jailbreak and root detection flagged two percent of sessions last month.
Ten questions from this glossary. Pick the right meaning for each term and see your score.
How to learn mobile app development vocabulary
Read real texts from the field regularly: Apple's and Android's developer documentation, the App Review Guidelines, Google Play policy pages, the release notes of the SDKs you use and GitHub issue threads.
Keep Xcode, Android Studio and at least one test device in English, so that error messages, settings and system dialogs match the words you will search for.
Learn platform pairs together: the same idea often has a different name on each platform, such as view controller and activity, keychain and Keystore, or phased release and staged rollout.
Use the right touch verbs: on a phone you tap, swipe, scroll, pinch and long-press; you do not click. The correct verb makes bug reports and test steps much clearer.
Write commit messages, bug reports and store release notes in English, even short ones, and reuse the collocations you see in this glossary.
Frequently asked questions
How can I learn English for mobile app development?
Read real texts from the field and notice how the words are used: Apple and Android documentation, App Store and Google Play review messages, SDK release notes, crash reports and GitHub issues. Learn each term with its partners (submit for review, fix a crash, request permission) and use new words right away in tickets, pull requests and release notes.
Which mobile development terms should I learn first?
Start with the words you hear in the first week: iOS, Android, native, cross-platform, SDK, emulator, simulator, screen, tap, background, push notification, permission, build, release, app review and crash. Then add store, monetization and performance vocabulary. This glossary is ordered the same way, from the most essential terms to more specialist ones.
What is the difference between an emulator and a simulator?
An emulator imitates a device's hardware and runs a real copy of the operating system; the Android Emulator works this way. A simulator only imitates how the software behaves and runs on the computer's own processor; Apple's iOS Simulator works this way. In daily conversation many developers use the two words interchangeably, but Android teams usually say emulator and iOS teams say simulator.
Should I say 'app' or 'application'?
Both are correct. 'App' is the normal word in speech, job ads, product plans and store pages. 'Application' sounds more formal and appears in documentation and technical names such as application ID or Application Not Responding. Remember that 'application' can also mean a job application, so the context matters.
Do Turkish mobile teams use the English or the Turkish terms?
Mostly a mix. Words such as build, release, crash, deep link, native and push are usually kept in English, often with Turkish endings ('build almak', 'crash oluyor'). Words such as uygulama, ekran, bildirim, izin, abonelik and önbellek are just as common. Knowing both lets you move easily between a Turkish stand-up and English documentation.
