The knight move is unusual among chess pieces. When it moves, it can move to a square that is two squares horizontally and one square vertically, or two squares vertically and one square horizontally. The complete move therefore looks like the letter L. Unlike all other standard chess pieces, the knight can 'jump over' all other pieces (of either color) to its destination square. It captures an enemy piece by replacing it on its square. The knight's ability to "jump over" other pieces means it tends to be at its most powerful in closed positions, in contrast to that of a bishop. The move is one of the longest-surviving moves in chess, having remained unchanged since before the seventh century. Because of this it also appears in most chess-related regional games. The knight moves alternately to light and dark squares.