File Extension APK
File extension APK is short for Android Package. This file extension is used by Android system to deliver and install application packages on Google Android operating system.
APK file has all information required to install application on Android system including code and resources.
To find out what is inside APK file you can use following trick. Change extension of APK file to ZIP and double click on it. Since APK is compressed using ZIP algorithm it will be opened by Windows and you will see its contents. Note that most of the information inside APK file is compiled code which is impossible to read. But you can extract images and other resources using this method.
Here is a quick instructions on how to install APK file on your Android device. First download APK file on your device using either Google Chrome or Android browser. Then navigate to the folder where you downloaded APK file and tap on APK icon. Once you do it an installation dialog with pop up. To install the application from APK file just click Install button in this dialog.
Below is a list of files which are typically included in APK package:
- META-INF directory
- MANIFEST.CF – manifest file
- CERT.RSA – certification file for the application
- CERT.SF – file with a list of resources and corresponding SHA-1 digests for all files described in manifest.cf
- lib – this directory contains compiled code of the application. It has multiple subdirectories in it each containing code for corresponding hardware platform
- res – directory with resources
- assets – assets of the application
- AndroidManifest.xml – Android manifest with name, version, access rights, referenced library files for the application.
- classes.dex – classes compiled in DEX format
- resources.arsc – file with precompiled resources