What is apk?

APK is acronym for Android’s Application Package which is used for installing the applications in Android devices. It is an archive of files in specific format and folder structure. Google Play is the official store for selling and sharing the Android applications.
APK is a package which contains all the necessary files required to install the application. And, allow it to run to acquire further resources, if required. The contents of APK file can be broadly divided into:

  • Application code,
  • Resources, and
  • Other files

Contents of APK

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    • CERT.RSA
    • CERT.SF
  • res
    • drawable-hdpi
    • drawable-ldpi
    • drawable-mdpi
    • drawable-xhdpi
    • layout
    • menu
    • and other resource directory created and used by developer
  • AndroidManifest.xml
  • classes.dex
  • resources.arsc

All APKs can be extracted using any archive extractor, but the files retrieved as a result may or may not be opened in any editor. While creating APK, all sources goes through some packaging and compressing algorithm. This also encrypts the files and signs with the Signing Key.