What is ReactDOMServer?

The ReactDOMServer object enables us to render components to static markup (typically used on node server). This object is mainly used for server-side rendering (SSR). The following methods can be used in both the server and browser environments:
1. renderToString()
2. renderToStaticMarkup()
For example, we generally run a Node-based web server like Express, Hapi, or Koa, and call renderToString to render our root component to a string, which we then send as response.