ReactStatelessFunctionalComponents.js

const Kitten = (props) => {
  return (
    <h1>Cats</h1> // put jsx in here
  )
}
// or
class Kitten extends React.Component {
  constructor(props) {
    super(props);
  }

  render() {
    return (
      <h1>Cat</h1>
    );
  }
}