React is the JavaScript UI library developed by Facebook. It was created by Facebook engineer Jordan Walke and first used internally for Facebook’s News Feed before being open-sourced in 2013.
React builds interfaces from reusable components, allowing developers to describe what the interface should look like for a given state. React then updates the displayed page when that state changes. This component-based model helped popularize modern single-page application development.
A common mix-up is calling React a complete framework. React is primarily a UI library; applications often add routing, data fetching, and build tools through projects such as Next.js or React Router. Angular, Ember, and Vue are separate projects, although Vue is also commonly described as a progressive framework.
React Native, released later, extended the React programming model to native mobile interfaces. It is related to React but is not the original browser UI library.