Intro

React is a front-end library for building user interfaces. It is maintained by Facebook and a community of individual developers and companies. React can be used as a base in the development of single page or mobile applications, as it is optimal for fetching data efficiently and rendering it on the web.
As of writing this, React is the most popular JavaScript library. It is used by over 1.5 million websites and apps, and is used by over 20% of the top 50 Fortune 500 companies.