Expo is a powerful open-source platform designed for building native mobile applications using JavaScript and React. It streamlines the development process by providing a suite of tools and services that simplify the creation, testing, and deployment of apps across iOS and Android. With Expo, developers can focus on building great user experiences without worrying about the complexities of native code. The platform is well-suited for both beginners and seasoned developers, offering an easy-to-use interface and comprehensive documentation.