In chess, a passed pawn is a pawn with no opposing pawns to prevent it from advancing to the eighth ; i.e. there are no opposing pawns in front of it on either the same or adjacent files. A passed pawn is sometimes colloquially called a passer. Passed pawns are advantageous because only the opponent's pieces can stop them from promoting.
In the diagram, the white pawns on b5, c4, and e5 are passed pawns, and Black's pawn on d4 is a passed pawn. If Black plays ...fxg4, then the black pawn on g4 will be passed, as well as White's pawn on f4.
Protected passed pawn
A passed pawn that is protected by its own pawns is called a protected passed pawn. In the first diagram in this article, the pawns on the b- and e-files are protected passed pawns. Two or more passed pawns on adjacent files are called connected passed pawns (see connected pawns), and they are very strong. In the diagram at the top, White's b- and c-pawns are connected passed pawns. A pair of connected passed pawns is sometimes called a steamroller. It is often strategically advantageous for the side with connected passed pawns to place them on the same rank and then advance them in tandem, because this makes them more difficult to .
Sometimes, minor pieces are sacrificed so that a pawn can have a clear path to promotion on the eighth rank. In the example illustrated (Mikhail Botvinnik–José Capablanca, AVRO 1938), in order to capitalize on the passed pawn on e6 and break its blockade by Black's queen, White continued 30. Ba3 Qxa3 31. Nh5+! gxh5 32. Qg5+ Kf8 33. Qxf6+ guaranteeing the e-pawn's promotion. The passed pawn's value is well worth the sacrifice of the bishop in order to clear its path to promotion. The only pieces preventing the e-pawn's promotion are the black queen and knight, and once they are gone, the pawn has a free path to promote. Black's pawns are also helpless to stop it.
Outside passed pawn
An outside passed pawn is a passed pawn that is separated by several files from the rest of the pawns and deflects the opposing king (and sometimes other pieces) from the defense of its other pawns. Such a pawn often constitutes a strong advantage for its owner because the opposing king does not have the range to cover both sides of the board.
In the diagrammed position from the fifth game of the 1971 Candidates match between Bobby Fischer and Bent Larsen, the outside passed pawn on the a-file confers White a winning advantage, even though is equal. The pawn will force Black's king to keep it from queening, leaving White's king free to capture Black's remaining pawns and win the game. White wins with: 41. Kd4 Kd6 42. a5 f6 43. a6 Kc6 44. a7 Kb7 45. Kd5 h4 If 45...f5 46.h4 wins. 46. Ke6 1–0
An outside passed pawn is also powerful in an endgame with . It is not so powerful in an endgame with rooks if the opposing rook can get behind the pawn (see diagram), as in the Tarrasch rule.
Passed pawns in the endgame
Passed pawns are particularly important, often of decisive significance, in the endgame. The position illustrated provides a dramatic example of this. White has no passed pawns and seems to be in desperate straits, since Black's king will soon attack White's pawns with ...Kg4. In fact, White by means of a sacrificial combination creates a passed pawn and wins: 1. g6 fxg6 (or 1...hxg6 2.f6! gxf6 3.h6!) 2. h6! gxh6 3. f6! and White's newly created passed pawn will queen. If it is Black's move, he must avoid this combination by playing 1... g6! (not 1...f6 2.h6!, nor 1...h6 2.f6!).