Query invalidation in React Query forces refetching of stale data after mutations, ensuring the UI stays synchronized with server state without manual cache updates. As the creator of CoreUI, a widely used open-source UI library, I’ve implemented query invalidation patterns in admin dashboards throughout my 11 years of React development. The most reliable approach is using queryClient.invalidateQueries in mutation callbacks to automatically refetch affected data. This method maintains data consistency across components without complex state synchronization logic.