Stalemate
The side to move has no legal move and is not in check. The game is a draw.
Black to move: the king on h8 is not in check, but every square it could go to is attacked, and Black has nothing else. A draw, however far ahead White was.
When you are winning, check before each move that the other side will still have a move.
New to chess? The examples here use it. Play your first moves (five minutes), then learn chess from the beginning, one short lesson at a time.