Concurrent Rendering, Priority Lanes, and React 19

Concurrent rendering represents a major paradigm shift in modern React. Candidates must understand how React separates urgent user inputs from non-blocking background renders using priority lanes.

Master useTransition to keep interfaces responsive during heavy computations, explore useDeferredValue for deferred search filtering, and learn modern React 19 paradigms including the use() API for promises, form actions with useActionState, and optimistic updates with useOptimistic.