Initially, it was developed by Jordan Walke, a software engineer at Facebook and maintained by Facebook. Later, it was used in other Facebook products like WhatsApp & Instagram. Facebook implemented ReactJS in its newsfeed section in 2011, but it was released to the public in May 2013.
The components are the heart of all React applications. These component are used to make a React application. Each component is responsible for outputting a small, reusable piece of HTML code and can be nested with other components to allow complicated applications.