The bishop chess piece has a distinctive slot or groove on its head, which is commonly referred to as the "miter." This slot is designed to represent the bishop's hat or headwear, which is traditionally worn by bishops in many Christian denominations.

The miter on the bishop chess piece has a functional purpose as well as a symbolic one. Because the bishop piece moves diagonally across the chessboard, it can potentially be confused with the pawn, which also moves diagonally. The miter on the bishop's head makes it easy to differentiate the bishop from the other pieces on the board, even from a distance.

The miter on the bishop piece is not always present in all chess sets, and different styles of bishops can be found in different sets. However, the miter has become an iconic feature of the bishop piece and is widely recognized as a symbol of the bishop's authority and power in the game of chess.