What is the meaning of mount?

Does mount mean the component is rendered? I’ve been learning the lifecycle of react, about the “componentDidMount”, “componentDidUpdate” and “componentWillUnmount” I’ve been confused, and I’ve checked the official documentation, it is still a problem for me, could you help me with this? what the usage of all of this?

  **Your code so far**

class MyComponent extends React.Component {
constructor(props) {
  super(props);
  this.state = {
    message: ''
  };
  this.handleEnter = this.handleEnter.bind(this);
  this.handleKeyPress = this.handleKeyPress.bind(this);
}
// Change code below this line
componentDidMount() {
  document.addEventListener("keydown", this.handleKeyPress)

}
componentWillUnmount() {
  document.removeEventListener("keydown", this.handleKeyPress)

}
// Change code above this line
handleEnter() {
  this.setState((state) => ({
    message: state.message + 'You pressed the enter key! '
  }));
}
handleKeyPress(event) {
  if (event.keyCode === 13) {
    this.handleEnter();
  }
}
render() {
  return (
    <div>
      <h1>{this.state.message}</h1>
    </div>
  );
}
};
  **Your browser information:**

User Agent is: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.127 Safari/537.36

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