| Article type | Reference glossary |
| Terms defined | 12 |
| Platforms covered | iOS and Android |
| Audience level | Everyday app users |
Why this glossary exists
App stores, settings screens, and support pages use technical vocabulary as if every reader already knows it. Most people do not, and that gap causes real friction: you skip an update because you have no idea what a "build number" signals, or you tap "allow" on a permission prompt without understanding what you are agreeing to.
This reference covers the terms you encounter most often when installing, using, or troubleshooting software. Each definition is written for someone who uses apps every day and wants to understand them better, not for someone who writes code. For a deeper look at how version numbers like 3.2.1 are structured and what each segment tells you, see how software version numbers work.
The terms, defined plainly
The definitions below are grouped loosely: the first set covers how apps are built and distributed, the second covers how they behave on your device, and the third covers what happens when something goes wrong or changes.
API
Application Programming Interface. A defined set of rules that lets two pieces of software exchange data. When a weather app shows a forecast, it is almost certainly pulling that data from a weather service's API.
Cache
A store of temporary data saved on your device so the app does not have to re-download it every time. Clearing the cache frees storage and can fix display glitches, but it may slow the app briefly while it rebuilds that data.
Build number
An internal identifier developers use to track exact versions of a release. Two apps can share the same version name (e.g., 4.1) but have different build numbers if one received a behind-the-scenes fix. See how version numbers are structured for more context.
Sandbox
An isolated environment where an app or piece of code runs without access to the rest of the system. Sandboxing limits the damage a buggy or malicious app can do to other apps or your data.
Beta
A pre-release version of an app that is functionally complete but still being tested. Beta versions may contain bugs and are usually intended for users willing to report problems in exchange for early access.
Permissions
Access rights an app requests from the operating system, such as the ability to read your location, use the microphone, or view your contacts. The OS asks you to grant or deny each permission, and you can change your choice later in device settings.
Push notification
A message sent from a server to your device without you opening the app first. The app must be installed and you must have granted notification permission for these to appear.
Background refresh
A setting that allows an app to fetch new data (messages, news, prices) while it is not open on screen. Disabling it for apps you rarely use can extend battery life.
Deprecation
A formal signal that a feature, API, or version of software is still functional but will no longer be updated and may be removed in a future release. Developers use this term to give users and other developers time to switch to a replacement.
Runtime
The environment that provides the resources an app needs to run on a device. On iOS, apps rely on Apple's runtime; on Android, they rely on the Android Runtime (ART). If a runtime is out of date, apps built for newer runtimes may not work correctly.
UI and UX
UI (User Interface) refers to the visual elements you interact with: buttons, menus, and screens. UX (User Experience) refers to the overall feel of using the software, including how logical the flow is. Both terms appear in app reviews and release notes.
Rollback
Reverting software to a previous version, usually after a problematic update. Most users cannot perform rollbacks themselves; developers or system administrators typically initiate them.
One term worth pausing on is permissions. When an app requests access to your camera, location, or contacts, it is asking the operating system to lift a restriction that is on by default. You can review and revoke permissions at any time in your device settings. Granting a permission is not permanent. For a broader look at how apps are reviewed before they reach you, the app store review and ranking process covers what approval pipelines actually check for.
Terms that appear when something changes or breaks
A few terms come up specifically when an app is updated, retired, or misbehaving. Deprecation means a feature or version is still available but no longer maintained; the developer has signaled it will eventually be removed. If an app tells you a feature is deprecated, it is worth finding the replacement before it disappears.
Force stop (Android) and offload (iOS) both remove an app from active memory, but they work differently. Force stop ends all background processes immediately. Offloading removes the app binary from storage while keeping your data, so reinstalling restores your settings and files. Neither action deletes your account or data stored on a server.
A crash log or diagnostic report is a file the operating system generates automatically when an app closes unexpectedly. Developers use these logs to trace where in the code something failed. When a support team asks you to share a crash log, they are looking at a timestamped record of the error, not your personal files.
Finally, rollback refers to reverting software to an earlier version. Most consumer app stores do not let users roll back on their own, but developers sometimes issue a rollback when a new release introduces a serious bug. If an app update causes problems and the developer has rolled it back, uninstalling and reinstalling from the store will restore the previous version.