A deep dive into React Fiber

React Fiber represents a significant overhaul of React's internal architecture, introduced in React v16 to enhance performance and introduce concurrency in rendering. Unlike the previous stack reconciler, Fiber allows React to pause, resume, and prioritize rendering tasks, improving user experience by managing updates efficiently within a 16ms frame budget to avoid dropped frames. Key features of React Fiber include asynchronous rendering, automatic batching of state updates, and support for new hooks like useTransition and useSyncExternalStore, which facilitate non-blocking updates and synchronization with external data sources. Since its inception, Fiber has been foundational for features like Suspense for data fetching and concurrent rendering, enabling React to defer non-urgent updates and hydrate server-rendered content selectively. The introduction of new APIs, such as createRoot and hydrateRoot, underscores a shift towards more advanced rendering capabilities, aiming to streamline transitions and optimize performance across applications.