React / Next.js

 revalidatePath — Server-side function that purges the Next.js cache for a given route so the next request re-fetches fresh data. 

"use server" — Directive marking a function/file as a Server Action, callable from the client but executed on the server. 

useFormStatus — Client hook that reads the pending/submitting state of the nearest parent <form>. useActionState — Client hook that wires a form to a Server Action and tracks its return value and pending state. 

useOptimistic — Client hook that shows an immediate optimistic UI update, then reconciles with the real server result. 

startTransition — React API that marks a state update as non-urgent so it won't block the UI (and can run async actions).

307 (Temporary Redirect) — Redirects to another URL while preserving the original HTTP method and body (e.g. POST stays POST), unlike 302 which can downgrade to GET.