What is a class component in React and how does it differ from a function component?

A class component is written using JavaScript class syntax and extends React.Component. It manages state using this.state and this.setState, and it needs a render method that returns the JSX to display. Function components with hooks can do everything class components can, using much simpler and shorter code, which is why almost all new React code today uses function components instead.

class Counter extends React.Component {
  constructor(props) {
    super(props);
    this.state = { count: 0 };
  }
  render() {
    return (
      <button onClick={() => this.setState({ count: this.state.count + 1 })}>
        Count: {this.state.count}
      </button>
    );
  }
}