React is a front-end library developed by Facebook. It is used for handling the view layer for web and mobile apps. ReactJS allows us to create reusable UI components. It is currently one of the most popular JavaScript libraries and has a strong foundation and large community behind it.

React can be used as a base in the development of single-page or mobile applications, as it's optimal only for its intended use of being the quickest method to fetch rapidly changing data that needs to be recorded.