React lifecycle methods define the sequence of events that occur over the lifetime of a React component, encompassing phases such as mounting, updating, unmounting, and error handling. These methods allow developers to execute code at specific points in a component's life, making tasks like initializing state, managing side effects, optimizing performance, and handling errors more manageable. In the mounting phase, methods like `constructor()`, `static getDerivedStateFromProps()`, `render()`, and `componentDidMount()` are utilized to set up initial state and perform DOM insertion. During the updating phase, methods such as `shouldComponentUpdate()`, `render()`, and `getSnapshotBeforeUpdate()` help manage changes in props or state, while `componentDidUpdate()` allows for actions after updates. The unmounting phase uses `componentWillUnmount()` for cleanup operations, like removing event listeners or canceling network requests. Error handling is facilitated by `static getDerivedStateFromError()` and `componentDidCatch()`, which allow components to manage errors and log them. Understanding these lifecycle methods is essential for building robust, efficient React applications.