An APK, short for Android Package Kit, is the file that contains an Android app: its code, resources, images and a manifest describing what the app needs. When you install an app from a store, an APK (or a set of split APKs) is downloaded and installed for you.
What is inside an APK
- Compiled code that the device runs.
- Resources such as layouts, images and translations.
- The manifest, which lists the app’s name, version and the permissions it asks for.
- A signature from the developer, used to check the app has not been changed.
Installing APKs safely
Installing an APK from outside an app store is called sideloading. Only install files from sources you trust, check that the app asks for sensible permissions, and keep apps updated. On a cloud phone, you can install apps from the store or upload an APK file to the phone.