Wohin? is a German interrogative adverb that translates to "where to?" or "to where?". It is used to ask about the destination or direction of movement. It implies a direction or a goal of a journey or action.
Specifically, wohin? asks about the destination of motion. It differs from "wo?" which translates to "where?" and asks about a location at which something is. For example, "Wo bist du?" means "Where are you?" (location), whereas "Wohin gehst du?" means "Where are you going?" (destination).
Wohin? is often used with verbs of motion such as gehen (to go), fahren (to drive), fliegen (to fly), laufen (to run), etc. It can also be used in a more abstract sense to inquire about the direction or purpose of a process or plan.