Understanding React(work in progress...)

React.js is a library to render UI. It does so with the help of React components. Any control you see on a webpage can be an outcome of react components. The objective of React component is to render some content on screen. So, here it is, your first component:

Function Component
function Greeting(){
 return <div>Greet People</div>
}

Above React component is a function component which is best suited if your component is only for rendering(other components can be used to hold any variable values, do some computations etc.). On the contrary, if you have some state of component, like a Form component may need to accept various inputs like name, age, location. These inputs are called state of component. These components are called class component as the class keyword is used to create such components. For such components, it is must to have a render method as:

Class Component
class Greeting(){
 render(){
  return (
   <div>Greet People</div>
  )
 }
}

and it allows us, the web engineers to do in a declarative way. When I say, declarative, I mean it allows us to first declare WHAT is that we are creating.

As an answer to "What is being rendered?", we have to jump to render method of a React component.