APK Writing

 Android packages contain all the necessary files for a single Android program. Below is a list of the most prominent files and folders:

• META-INF/: Contains the manifest file, signature, and a list of resources in the archive
• lib/: Native libraries that run on specific device architectures (armeabi-v7a, x86, etc.)
• res/: Resources, such as images, that were not compiled into resources.arsc
• assets/: Raw resource files that developers bundle with the app
• AndroidManifest.xml: Describes the name, version, and contents of the APK file
• classes.dex: The compiled Java classes to be run on the device (.DEX file)
• resources.arsc: The compiled resources, such as strings, used by the app (.ARSC file)