JSX and Rendering elements

This is neither a string nor HTML,it's JSX.

JSX or Javascript XML, is an XML/HTML-like syntax used by react that extends ECMAScript(ES) so that XML/HTML-like-text can co-exist with Javascript/React code.

Since JSX is closer to Javascript than to HTML,ReactDOM uses camelCase property naming convention instead of HTML attribute names.
For eg :
class becomes className
tabindex becomes tabIndex

Let's say there is a somewhere in your HTML file :

# This is the 'root' DOM node because everything inside it will be managed by ReactDOM.

To render a React element into a root DOM node, pass both to ReactDOM.render() :

Running you react app after this will give the following output :

That's all folks.
Thanks for reading!