The component lifecycle has three distinct lifecycle phases:
Mounting: The component is ready to mount in the browser DOM. This phase covers initialization from
componentDidMount() lifecycle methods.
Updating: In this phase, the component get updated in two ways, sending the new props and updating the state either from
forceUpdate(). This phase covers
componentDidUpdate() lifecycle methods.
Unmounting: In this last phase, the component is not needed and get unmounted from the browser DOM. This phase includes
componentWillUnmount() lifecycle method.
It's worth mentioning that React internally has a concept of phases when applying changes to the DOM. They are separated as follows
Render The component will render without any side-effects. This applies for Pure components and in this phase, React can pause, abort, or restart the render.
Pre-commit Before the component actually applies the changes to the DOM, there is a moment that allows React to read from the DOM through the
Commit React works with the DOM and executes the final lifecycles respectively
componentDidMount() for mounting,
componentDidUpdate() for updating, and
componentWillUnmount() for unmounting.