React: What is React concurrent rendering?

Concurrent rendering — React can interrupt rendering.

Features:

• Interruptible rendering
• Priority-based updates
• Offscreen rendering

1const [isPending, startTransition] = useTransition();
2startTransition(() => {
3  setFilteredResults(computeExpensive(data));
4});

Benefits: Responsive UI during heavy computation, no jank, better UX.

Requirements: React 18+, Strict Mode, proper key usage, pure render functions.