What is an APK file?
An APK (Android Package) is the file an Android app is installed from. It's really a ZIP archive holding the app's code, images, a manifest that lists what the app is and the permissions it wants, and the developer's digital signature.
Inside you'll find AndroidManifest.xml (the app's ID card), classes.dex (its compiled code), res/ (images, layouts and text), sometimes lib/ with native code for specific processors, and signing information. Your own data is never in an APK. It's created later in the app's private storage.
Apps from Google Play usually arrive as a base APK plus small split APKs tailored to your phone, built from an App Bundle the developer uploads. An APK you download from a website didn't come through that process, so check where it really came from.
- Get apps from an official store where you can
- If you download an APK, only take it from the developer's own website
- Keep Google Play Protect on, since it checks apps from any source at install
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What's in an APK
From the Inside an APK course. Unzip a real-looking app package and learn what each part does.