In the game of chess, a sacrifice is the deliberate giving up of a chess piece by a player, allowing or even forcing the opponent to capture it. A sacrifice could also be a deliberate exchange of a chess piece of higher value for an opponent's piece of lower value. Ordinarily, if a player loses a chess piece or exchanges it for a lower value piece, it is detrimental to one's game, decreasing one's chances of winning and/or increasing the chances of losing the game. However, a sacrifice of a chess piece is offered or made with the intention of improving one's situation in a game, increasing one's chances of winning and/or the decreasing chances of losing the game. To be a sacrifice, the piece is deliberately given up by the sacrificing player, not lost due to oversight (such as a blunder) or forced capture. However even though a sacrifice is made with the intention of bettering one's game, a sacrifice can still turn out to be a mistake. A sacrifice is one of numerous possible chess tactics, sometimes used in combination with other types of tactics.
Any type of chess piece except the king can be sacrificed, although the availability of pawns en prise is rather common in chess games and the rather routine loss of a pawn (a rather low value piece) is often not called a sacrifice. However, some pawns are key factors in some game situations and deliberate offering and loss of such key pawns could still be considered pawn sacrifices. An undue emphasis on hunting and capturing enemy pawns while ignoring more important aspects of a game is called pawn grabbing.
Because loss of a piece, especially a valued one, is ordinarily bad for a player's game, a sacrifice or the offering of one often seems superficially anti-logical and is often an unexpected or surprise move. The surprise sacrifices of a queen, a high value piece, or of multiple pieces are often considered to be the most showy sacrifices.
Benefits of sacrifices
A sacrifice is often part of a tactical combination in a chess game. Some unusual or elaborate combinations may involve sacrificing more than one piece.
A common benefit of making a sacrifice is to allow the sacrificing player to checkmate the opponent. Since checkmate is the ultimate way to win a chess game, the loss of material (value of chess pieces) should not matter in a successful checkmate. Such sacrifices are often actually exchanges of a higher value piece sacrificed to capture a pawn covering the opposing king or to cature another covering or defending lower value piece. In sacrifices leading to checkmate, the opponent is often forced to capture the sacrificed piece. Many of the moves in a checkmating combination can be checks with one or few options for the opponent to respond with. In this way a sacrifice can often lead to a forced checkmate even after a number of moves.
Another possible benefit of a sacrifice is that it leads to a combination which eventually results in an overall loss of material for the opponent, making the upfront investment of a sacrifice worthwhile for the sacrificing player. Even if the overall exchange of material value is even or a slight loss overall, the sacrificing player may benefit due to the situation of the game; for example, the sacrificing player may be ahead in material already and even further exchanges would weaken the opponent's army. A player ahead in material may decide it is worthwhile to get rid of one of the last effective or interfering pieces the opponent has.
Another possible benefit of a sacrifice could be to improve ones position strategically. Gambits are sacrifice offers in the opening which can be accepted or declined with the goal of improving ones strategic position if they are accepted (or possibly declined). Gambits are usually pawn offers.
Another possible use of a sacrifice could be part of a combination to allow one of the player's advanced pawns to be promoted to a queen. Sacrifices can also be made for defensive reasons such as avoiding being checkmated, avoiding even more loss of material or a bad position, capture of a pawn which would inevitably be promoted to a queen, or trying to get a draw by stalemate or perpetual check.