# React Server Side Rendering (SSR)

For React, it means we render the React components from server side before sending to browser.

Advantage:

• To avoid loading blank screen (FOUC issue) initially for the user (better user experience)
• Page is sent pre-populated from server, fast load [performance optimization]
• Better for SEO

React itself is isomorphic (universal) which means it doesn't contain any browser specific code, just the JavaScript can run both on the browser and the server.

Isomorphism for web development means rendering web pages on both the server and client side.

Isomorphic React: means server renders the initial HTML for the client using React components and React.renderToString(). (Purpose: to avoid FOUC issue occurs)

Using renderToString function to generate the static markup HTML code later rendering at browser side (Don't forget we introduce building (code compiling) systems like babel for converting JSX, ES6 code to be like readable JavaScript code)

Another tiny concept: hydrate(): its similar with render method, but it uses to hydrate a container to render HTML DOM by using ReactDOMServer.

Purpose of JSX: allow developers to write HTML in JavaScript and place them in the DOM without any createElement or appendChild methods. (Easier to read for React app)