You can use plug-ins developed for Android to call Java and C++ code created outside of Unity from your C# scripts. This allows you to access features like OS calls and third-party code libraries that would otherwise not be available to Unity. For more information about using plug-ins with Unity, see documentation on plug-ins.
The following pages describe the process of creating your own plug-ins for use in Android projects. The information on these pages assumes you already know how to create native plug-ins for Unity. For more information about native plug-ins and their uses, see documentation on native plug-ins.