Quick answer
An Android Package Kit (APK) is the file format Android uses to distribute and install apps. Google now prefers the Android App Bundle (AAB) format for Play Store distribution.
What it is
An APK is a ZIP archive containing an Android app's code, resources and manifest. It is what Android installs when you side-load an app. For Play Store distribution, Google prefers AAB, which generates optimised APKs for each device.
Why it matters
If you distribute outside the Play Store (beta tests, enterprise apps), you will deal with APKs. For Play Store, use AAB and let Google generate APKs.
How to use it
- Build AAB for Play Store distribution.
- Use APK for direct distribution and internal testing.
- Sign with the right certificate for distribution.
Examples
- Internal testing tracks on the Play Console use AAB.
- Side-loaded apps from your website use APK.