APK expansion files

APK expansion files are the asset splitting solution for the APKThe Android Package format output by Unity. An APK is automatically deployed to your device when you select File > Build & Run. More info
See in Glossary publishing format. They enable an application to split its assets into:

• Core assets like scriptsA piece of code that allows you to create your own Components, trigger game events, modify Component properties over time and respond to user input in any way you like. More info
  See in Glossary, plug-insA set of code created outside of Unity that creates functionality in Unity. There are two kinds of plug-ins you can use in Unity: Managed plug-ins (managed .NET assemblies created with tools like Visual Studio) and Native plug-ins (platform-specific native code libraries). More info
  See in Glossary, and assets that the application requires for the first sceneA Scene contains the environments and menus of your game. Think of each unique Scene file as a unique level. In each Scene, you place your environments, obstacles, and decorations, essentially designing and building your game in pieces. More info
  See in Glossary.
• Additional assets like Streaming Assets and assets that the application requires for additional scenes.

The core assets go in the main APK file and the additional assets go in APK expansion files.

Digital distribution services often have an application size limit. This makes it necessary for APK applications that are larger than the size limit to use APK expansion files. For example, Google Play requires applications that are larger than 100MB to use APK expansion files. It allows you to use two APK expansion files, the main APK expansion file, and the patch APK expansion file, which can be up to 2GB each. For more information, see APK Expansion Files.

This section of the documentation introduces APK expansion files and explains how to work with them in Unity.