What is React

React is a fast, component-based, front-end JavaScript library. React typically runs in your browser and renders single-page web application user interfaces (and thanks to React-Native, mobile application user interfaces as well).

React breaks web elements down into re-usable components making it easy to manage complex web interfaces.

React’s virtual DOM makes rendering updates fast and efficient. The Virtual DOM is a JavaScript representation of the actual DOM. When updates are made React compares the current DOM to the virtual DOM and only updates the differences between the two.

React uses declarative JSX which is an HTML-style syntax inside of JavaScript. React components can be reused and declared using JSX. The Babel compiler converts JSX to JavaScript which renders the HTML view.

React handles the majority of DOM rendering, so your index.html file begins as a simple div where React will append the DOM elements.

Next we’ll walk through making a React component.