How Android works
APKs & installation
What is actually inside an APK, and what happens when you install one.
5 pages53 min5 interactive6800 words
- 01Anatomy of an APKAn APK is a ZIP file with a strict internal contract: binary manifest, compiled resources, DEX code, native libraries, and a signature that covers the whole archive. Learn the parts and install failures stop being mysterious.beginner11 mininteractive
- 02The resources systemResources are the reason one APK can serve a hundred languages, five densities and two themes. The mechanism is a compiled table plus a fixed precedence order — and you can learn it by playing with it.intermediate11 mininteractive
- 03App BundlesAn App Bundle is a publishing format, not an install format. You upload one file; Play generates a different set of APKs for every device — and that change is why APKs are no longer universal.intermediate10 mininteractive
- 04The install flowInstalling is a transaction with a signature check, a data directory, a dexopt pass and a broadcast. It is also one of the platform's most security-sensitive paths — and the rules for who may install what keep tightening.intermediate10 mininteractive
- 05Package visibilityBefore Android 11, any app could enumerate every installed app. Since API 30 it can only see what it declares an interest in — a change that broke a generation of apps and revealed how much they depended on the full list.intermediate11 mininteractive
Test yourself
Test yourself: APKs & installation
An APK is fundamentally which kind of file?