An APK file is a file format used by the Android operating system and other Android-based operating systems for distribution and installation of mobile apps, mobile games, and middleware). APK stands for Android Package Kit, and it is similar to other software packages such as APPX in Microsoft Windows or a Debian package in Debian-based operating systems). An APK file is a type of archive format, similar to ZIP files, that contains multiple files and metadata in them.

To make an APK file, a program for Android is first compiled using a tool such as Android Studio or Visual Studio, and then all of its parts are packaged into one container file). An APK file contains all of a programs code (such as .dex files), resources, assets, certificates, and manifest file). APK files can be generated and signed from Android App Bundles).

APK files can have any name needed, but it may be required that the file name ends in the file extension for being recognized as such). APK files can be opened on Android platforms, as well as on Windows and Mac OSes. Android users typically dont see APK files, as Android handles the app installation process through Google Play. However, other websites may offer direct APK file downloads for users to install apps manually.

The contents of an APK file include the AndroidManifest.xml, which is an additional Android manifest file that describes the name, version, access rights, library, and other contents of the APK file, and assets/, which are application assets and resource files included with the app. APK files contain all contents needed to run the application, including the code, resources, and assets.