and a knight, or two knights. A player possessing a pair of bishops has a strategic weapon in the form of a long-term threat to trade down to an advantageous endgame. Two bishops on opposite-colored squares and king can force checkmate against a lone king, whereas two knights cannot. A bishop and knight can force mate, but with far greater difficulty than two bishops. In certain positions a bishop can by itself lose a move (see triangulation and tempo), while a knight can never do so. The bishop is capable of skewering or pinning a piece, while the knight can do neither. A bishop can in some situations hinder a knight from moving. In these situations, the bishop is said to be "dominating" the knight. On the other hand, in the opening and middlegame a bishop may be hemmed in by pawns of both players, and thus be inferior to a knight which can jump over them. A knight check cannot be blocked but a bishop check can. Furthermore, on a crowded board a knight has many tactical opportunities to fork two enemy pieces. A bishop can fork, but opportunities are more rare. One such example occurs in the position illustrated, which arises from the Ruy Lopez: 1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.0-0 b5 6.Bb3 Be7 7.d4 d6 8.c3 Bg4 9.h3 Bxf3 10.Qxf3 exd4 11.Qg3 g6 12.Bh6 Game use Good bishop and bad bishop In the middlegame, a player with only one bishop should generally place friendly pawns on squares of the color that the bishop cannot move to. This allows the player to control squares of both colors, allows the bishop to move freely among the pawns, and helps fix enemy pawns on squares on which they can be attacked by the bishop. Such a bishop is often referred to as a "good" bishop. Conversely, a bishop which is impeded by friendly pawns is often referred to as a "bad bishop" (or sometimes, disparagingly, a "tall pawn"). The black light-squared bishop in the French Defense is a notorious example of this concept. A "bad" bishop, however, need not always be a weakness, especially if it is outside its own . In addition, having a "bad" bishop may be advantageous in an opposite-colored bishops endgame. Even if the bad bishop is passively placed, it may serve a useful defensive function; a well-known quip from GM Mihai Suba