React Fiber

React Fiber is an internal engine in React that manages how user interfaces are built and updated efficiently. It breaks down complex UI changes into smaller, manageable tasks, allowing React to prioritize important updates, pause and resume work, and handle multiple tasks seamlessly. This system improves performance, responsiveness, and flexibility, ensuring applications stay smooth even during large changes or slow connections. Essentially, React Fiber is like a smart coordinator that organizes and optimizes the process of updating your app’s interface, making it faster and more reliable.