React (React.js)

React (React.js) is a popular JavaScript library used to build user interfaces, especially for web applications. It allows developers to create reusable components—small, self-contained pieces—that dynamically update and display data efficiently. React manages how the interface looks and responds to user interactions, making websites faster and more interactive. It works by constructing a virtual representation of the webpage, which it compares to the real one to update only the necessary parts, improving performance. Overall, React simplifies building complex, responsive web pages, enhancing both development efficiency and user experience.