Underpromotion avoids the stalemate trap in chess

Underpromotion in chess consists of transforming a pawn that has reached the last rank into a piece other than a queen. This tactical choice sometimes allows avoiding a draw by stalemate, a trap into which white would fall if they chose the all-powerful queen in certain positions. To illustrate this, transforming the pawn into a rook allows offering a legal move to the opposing side, such as the g7 square for the black king, thus authorizing victory.