React is a JavaScript library for building user interfaces.
React makes it painless to create interactive UIs. Design simple views for each state in your application, and React will efficiently update and render just the right components when your data changes. It can be categorized as “V” in the MVC (Model-View-Controller) pattern.

Advantages of React for a front end developer

1. Easy to use
2. It Supports Reusable Component in Java
3. Easier Component Writing
4. Better Performance with Virtual DOM
5. SEO Friendly

GETTING STARTED WITH REACT
Install NodeJS
Run on the command prompt npx-craete-react-app name of the app
Run cd name of the app to open the folder
Start coding
To run the app run npm start on the command prompt
To build the app run npm start build on the command prompt.

REACT IS COMPONENT-BASED

Build encapsulated components that manage their own state, then compose them to make complex UIs.
Since component logic is written in JavaScript instead of templates, you can easily pass rich data through your app and keep state out of the DOM.

REACT COMPONENTS

React components implement a render() method that takes input data and returns what to display. This example uses an XML-like syntax called JSX. Input data that is passed into the component can be accessed by render() via this.props(short for properties).React component is easier to write since it uses JSX, an optional syntax extension for JavaScript that allows you to combine HTML with JavaScript.