React is a modern, web development framework that allows developers to create and reuse components that make up a website or application. Each component contains its own logic and controls, and is reusable throughout the application. The components follow a unidirectional data flow. This makes it easier to debug errors and isolate problem locations.

React components are usually written in JavaScript or JSX, an extension of JavaScript that has features similar to HTML, such as registering event handlers for UI elements. Each React component implements a render method that returns JSX corresponding to the UI of the component. This code is then translated into browser-compatible HTML.

Another benefit of using React is that you can program much faster than with traditional web frameworks. This is because React does not reload the entire page every time a user interacts with the page. Instead of reloading the entire page, React updates the relevant sections only. This improves the user experience, and is also better for SEO.

React also promotes a cleaner code structure. Because React is modular, you can reuse code without worrying about the complexity of the code. This makes reusing components easy for developers and helps maintain application stability. React JS is an excellent choice for web development and thousands of companies use it in their applications.