React: A Powerful JavaScript Library for Building User Interfaces

React is an open-source JavaScript library used for building user interfaces. It was developed by Facebook and is now maintained by a community of developers. React allows developers to create reusable UI components and manage the state of those components efficiently. It uses a virtual DOM (Document Object Model) to update the UI in an efficient manner, making it quick and responsive. React can be used with other libraries or frameworks, such as Redux, to create complex applications. It is widely used in front-end web development and mobile app development.