React Fiber is an internal reimplementation of the React reconciler algorithm, introduced by the React team to improve the performance and rendering capabilities of React applications. It was first announced by Facebook in 2017 and has since become a fundamental part of the React library.
Incremental Rendering: Fiber divides the rendering work into smaller units, enabling it to yield control back to the browser whenever necessary, improving the application's responsiveness.
Concurrency: Fiber introduces the ability to work on multiple tasks concurrently, making it easier to prioritize updates and efficiently manage rendering.
Error Boundaries: Fiber introduces a new error-handling mechanism called Error Boundaries, which allows developers to catch errors in the component tree and display a fallback UI.
Scheduling: Fiber's scheduling mechanism helps to prioritise and manage updates more efficiently, ensuring that high-priority updates are processed before lower-priority ones.