A block is a defensive tactic in chess in response to an attack, consisting of interposing a piece between the opponent's attacking piece and the piece being attacked. This type of blocking will only work if the attacking piece is a type that can move linearly an indefinite number of squares such as a queen, rook, or bishop and there is at least one empty square in the line between the attacking and attacked piece. Blocking is not an option when the attacking piece is directly adjacent to the piece it is attacking, or when the attacking piece is a knight (because knights "jump over other pieces" and cannot be blocked). When an opponent's attack on a piece is blocked, the blocking piece is to some extent pinned, either relatively or absolutely, until a future move by either side allows it t