Native Modules
Used to access native APIs of the Platform, reuse 3rd party libraries written directly for the platforms, or write high-performant, multi-threaded code (e.g. image processing).
The NativeModule system exposes instances native classes to JS as objects, allowing to execute native code from within JS.
💡 React Native Team is working on TurboModules which are going to be the next big thing in the Native Modules world.