Check and checkmate

A position in which the king is attacked and must be made safe on the immediate move.

A legal move that removes the immediate attack on the player’s own king.

Interposition stops a rook, bishop, or queen check by placing another piece between the attacker and the king.

A discovered check occurs when one piece moves away and uncovers another piece's attack on the king.

Double check occurs when one move leaves the king attacked by two pieces at the same time.

An illegal result created by moving so that the moving side's king remains or becomes attacked.

A check with no legal defense, ending the game immediately in victory for the attacking player.

Perpetual check is a forced sequence of repeated attacks on the king that can return to the same cycle again and again.