is of roughly equal value to a knight. In certain circumstances, one can be more powerful than the other. If the game is "closed" with many interlocked pawn formations, the knight tends to be stronger, because it can hop over the pawns while they block the bishop. A bishop is also weak if it is restricted by its own pawns, especially if they are blocked and on the bishop's color. Once a bishop is lost, the remaining bishop is considered weaker since the opponent can now plan their moves to play a white or black color game. In an with action on both sides of the board, the bishop tends to be stronger because of its long range. This is especially true in the endgame; if passed pawns race on opposite sides of the board, the player with a bishop usually has better winning chances than a player with a knight. A king and a bishop is not sufficient material to checkmate an opposing lone king, but two bishops and a king checkmate an opposing lone king easily. Rooks Rooks have more scope of movement on half-open files (ones with no pawns of one's own color). Rooks on the seventh rank can be very powerful as they attack pawns that can only be defended by other pieces, and they can restrict the enemy king to its back rank. A pair of rooks on the player's seventh rank is often a sign of a winning position. In middlegames and endgames with a passed pawn, Tarrasch's rule states that rooks, both friend and foe of the pawn, are usually strongest behind the pawn rather than in front of it. A king and a rook is sufficient material to checkmate an opposing lone king, although it's a little harder than checkmating with king and queen; thus the rook's distinction as a major piece above the knight and bishop. Queen Queens are the most powerful pieces. They have great mobility and can make many threats at once. They can act as a rook and as a bishop at the same time. For these reasons, checkmate attacks involving a queen are easier to achieve than those without one. Although powerful, the queen is also easily harassed. Thus, it is generally wise to wait to the queen until after the knights and bishops have been developed to prevent the queen from being attacked by minor pieces