What is APK?

An APK (Android Package Kit) is the package file format used by the Android operating system for distribution and installation of mobile apps and middleware. It is analogous to other software package formats such as .exe, .dmg, or .deb. An APK file contains all of the program's code (such as .dex files), resources, assets, certificates, and manifest file. It is used to distribute and install applications on Android devices.