React Native is a popular open-source framework for building mobile applications using JavaScript. It was developed by Facebook and allows developers to create cross-platform apps for iOS and Android with a single codebase. This means that instead of writing separate code for each platform, developers can use React Native to build apps that look and feel native on both iOS and Android devices. With its efficient and intuitive development process, React Native has become a go-to choice for many developers looking to build high-quality mobile apps quickly and easily.