React Native is a cross-platform framework for building real iOS and Android apps using JavaScript or TypeScript with React, rendering UI via native views (e.g., View, Text, Image) rather than the web. You compose reusable components, manage state with familiar React patterns, and access device features through a lightweight native bridge or by writing custom Native Modules in Swift/Objective-C or Kotlin/Java when you need extra performance or platform APIs. It offers Fast Refresh for tight dev loops, strong TypeScript support, and a thriving ecosystem for navigation, styling, testing, and animations. Teams can start quickly with Expo for managed builds and OTA updates, or choose the bare workflow for full control over native code. React Native excels when you want one codebase, native feel, and rapid iteration, with trade-offs like larger binaries and occasional platform-specific work for cutting-edge features.