Explain React concurrent rendering

Concurrent rendering allows React to interrupt rendering work and prioritize urgent updates to keep the UI responsive.

Concurrent rendering in React 18 introduces a new rendering model where rendering work can be paused, interrupted, or resumed. Instead of blocking the main thread until the entire tree renders, React schedules updates based on priority. This is powered by the Fiber architecture and a cooperative scheduling model. It improves responsiveness by allowing urgent updates (like typing) to be processed before heavy background rendering tasks.