why do we using props in react code example

Example 1: props in react

function Welcome(props) {
  return 
Hello, {props.name}
;
}

function App() {
  return (
    

                      
  );
}

ReactDOM.render(
  ,
  document.getElementById('root')
);

Example 2: pass props in react

/* PASSING THE PROPS to the 'Greeting' component */
const expression = 'Happy';
 // statement and expression are the props (ie. arguments) we are passing to Greeting component

/* USING THE PROPS in the child component */
class Greeting extends Component {
  render() {
    return 
{this.props.statement} I am feeling {this.props.expression} today!
;
  }
}