Mobile app
A program made to run on a phone or tablet, usually installed from an app store.
A mobile app is a program built for a phone or tablet: your bank, WhatsApp, the maps, the camera. Unlike a website, it is installed on the device, so it can use the camera, GPS, notifications, Face ID or fingerprint, and keep working partly offline. Almost all phones run one of two operating systems, iOS (Apple) or Android (Google), and an app has to be built for each.
Apps reach your phone through an app store: Apple's App Store or Google Play, plus a few alternatives on Android. The developer uploads the app, the store reviews it against its rules, and then publishes it. Stores also handle payments and take a commission on purchases and subscriptions, which is why some apps send you to their website to pay.
Most apps are only the front of a bigger system. The app shows screens and reacts to your taps, but the data (your messages, your balance, your orders) lives on servers it talks to through an API. Teams build native apps in each platform's own language, Swift for iOS and Kotlin for Android, or use cross-platform frameworks like Flutter or React Native to write one codebase for both.
Keep in mind
- Built for iOS or Android, or both through a cross-platform framework.
- Distributed through app stores that review it and take a commission.
- Can use phone hardware: camera, GPS, notifications, biometrics.
- Most of the data usually lives on a server, reached through an API.
