React is an open-source JavaScript library used for building user interfaces (UIs), especially single-page applications (SPAs). Developed by Facebook (now Meta), React allows developers to build fast, interactive, and reusable UI components for web and mobile apps.
Unlike traditional page reloads, React updates only the parts of the page that change. This makes web applications faster, smoother, and more efficient.
Think of React as LEGO blocks – you can build small reusable pieces (components) and then combine them to make large applications.