Chess strategy describes concepts for success in the highly strategic game of chess. Experts tend to divide the study of into two different categories: strategy and tactics, and into three consecutive stages in a game: the opening, middle game, and endgame. Tactics might be described as short-term plans for sequences of moves; it involves studying manoeuvres, such as combinations, and how those manoeuvres might lead to a gain in material or improvements in a player's strategic position. Strategy refers to the study of long-term improvements to a player's position, such as control of the center of the board, protection of the king, pawn structure, placement of the pieces, and other considerations.
In the game of chess, some pieces are considered more valuable than others. As a result, much of strategy in chess centres around trying to gain an advantage in "material". This is accomplished by having more pieces, or more valuable pieces on the board. In the study of chess, the pieces are assigned a point value:
- Pawns are worth 1 point
- "Minor" pieces, bishops and knights, are worth 3 points
- Rooks are worth 5 points
- The queen is worth 9 points
- The king, while worth the whole game, has in the endgame a fighting value of 4 points
Much of the study of tactics revolved around the value of material: a player will not trade off a queen for two bishops, even though they would have more pieces on the board, because the pieces left would have less value.
The point values are also relative; for example, in endgames with pawns on only one side of the board, knights are often preferred to bishops, because a bishop can only operate on squares of their color, while in endgames with pawns on both sides, a bishop is often preferred, because they can move more quickly to both sides of the board. Having two bishops is also generally considered better than having a knight and a bishop or two knights, because the bishops can work together by attacking both colors of squares.
Tactics are manoeuvres in chess that are usually used to gain material, avoid loss of material, checkmate the opponent, or avoid checkmate or loss of a game. Some examples include
- Fork: A move where one piece is moved to attack two or more opposing pieces simultaneously, in the hope that the opponent will only be able to move one of his/her pieces from the attack and leave the other piece(s) available for capture. Any type of piece can fork an opponent's pieces. A fork may or may not involve a check of the opponent's king as one of the pieces being attacked. The general type of fork is named after the type of piece moving to simultaneously attack. For example, in a knight fork, a knight is moved to simultaneously attack two or more opponent's pieces.
- Pin: A piece is considered "pinned" when it cannot move, because, by moving, it would expose a more valuable piece to capture. An absolute or "hard" pin is when a piece is pinned to the king, and thus cannot legally move; whereas a relative or "soft" pin occurs when the piece is pinned to a valuable piece, such as the queen. Additional attacks on the pinned piece by the opponent may be called working the pin.
- Skewer: A skewer occurs when a piece attacks an opponent's valuable piece in order to force it to move, and thus capture an opponent's piece located behind. Placing the king in check with a rook or queen, and forcing it to move, in order to take a rook that is located behind the king, is an example of a skewer.
- Discovered attack: A discovered attack occurs when a player's piece moves out of the way of (unblocks) a linear attack by one of his/her pieces on an opposing piece. If the unblocked attack is on the opponent's king, this move is called a discovered check. The piece moving out of the way may also cause an attack of its own, resulting in an overall double attack by that player.
- Exchange: An exchange [of pieces] occurs when each player captures an opponent's piece in a sequence of closely related moves. Exchanges may be used in combination with other tactics to gain an advantage or avoid incurring a disadvantage.
- Counterattack: A counterattack is a response to an attack with an opposing attack, often just as serious or more serious, perhaps a check. It may sometimes work as a defensive manoeuvre to avoid net loss of material from another tactic.
- Sacrifice: A deliberate giving up of a piece by its player, allowing or forcing the opponent to capture it, possibly in exchange for a less valuable opposing piece.
- Combination: A series of sequential moves which may involve any combination of tactics leading to checkmate, some other gain, or avoidance of loss.
- Forced three-fold repetition or forced stalemate for a draw to avoid loss of a game.
Opening, middle, and end games
For the sake of strategy and general flavor and discussion of chess, the duration of a chess game can be inexactly partitioned into three general stages: the opening, the middlegame, and the endgame. The opening is at the start of a game, so every chess game will have an opening phase. Some short games may end in the opening stage, but most reach the next stage, the middlegame. Numerous games can end before the last phase, the endgame, is reached, but many games will survive to reach the endgame. There are typically no exact points in a game when one stage ends and the next begins. Instead, there are commonly gradual and subjective transitions between these stages.
See main article chess opening.
The opening of a chess game is perhaps the first ten to twenty moves for each player. For reasonably strategy-minded players, the opening consists of setting up the initial pawn structure, developing the non-pawn pieces, and often castling. Some maneuvering for position or control of the center of the board, or for space in general can occur in the opening, but many advanced players prefer to wait until initial development is finished before starting a serious attack on the opponent, often waiting until the middle game. Development of a piece refers to the initial one or possibly two moves of a non-pawn piece, basically getting it out of the starting square on the back rank and set it on an effective square.
Openings are extremely important in the game of chess. There are volumes of chess literature devoted solely to the study of a certain sets of moves: the Spanish, the Italian, the Sicilian, the French, the English, etc. are all different sets of opening moves.
Classical opening strategy tends to center around several strategic principles. First, a player should attempt to control and occupy the center of the board with their pieces. Secondly, a player should attempt to make their position more free, by allowing their pieces space to operate in. Thirdly, a player should try to castle, so that their king is out of the center of the board and protected, and so that their rook is moved out of the corner and can be more useful.
Another school of thought, known as "hypermodern" opening theory, disputes the idea that a player must occupy the center of the board to be effective. In this school of thought, a player is encouraged to control the center by controlling the sides, and allowing the opponent to overextend himself in the center of the board, setting up a counterattack. Many of the Sicilian (1.e4 c5), English (c4) and Reti (1.Nf3 d5 2. c4) systems are considered hypermodern, or are derived from hypermodern theory.
The middlegame in chess is very complicated, but very little chess literature is dedicated to it. It generally centers around both players trying to find room for their pieces. Sometimes one player will attack the other's position. Also, both players will try to get their rooks onto open, or half-open files; an open file is a column of squares in which neither player has a pawn, while a half-open file is one in which only the opponent has a pawn. Both allow the rook more freedom in transitioning to the endgame, and may allow the rook to invade the opposing position.
The endgame is when most of the pieces are traded off, and each player attempts to win, generally by forcing a promotion of a pawn to a queen. The type of endgame is generally defined by the pieces still remaining on the board.
Endgames are automatic draws in situations where a win is technically impossible. Such automatic draws include situations where only the kings are remaining, or when one player has a king and the other has a king and one knight or one bishop. Often a player with less material or another disadvantage will try for a draw through perpetual check, a triple-repeat of the same position, or a stalemate.
Rook and pawns: These are the most common endings, because the rooks are located in the corners of the board to begin with, so they usually take a while to enter the game. Having a rook "on the seventh" or located on the row where the opponents pawns began is often advantageous in rook and pawn endings, as undefended pawns can be attacked.
Piece and pawns: These endings happen when there are one or more "minor" pieces (bishops and knights).
King and pawns: These endings occur when all of the pieces except the kings have been traded off. They are considered extremely "sharp", in that one wrong move will usually cost a player the game. In many cases, an advantage of a single pawn is sufficient to force a win. Many of these endings also come down to "tempo", or which player is forced to move first.
Queen and pawns: Queen and pawn endings occur when there are still queens left on the board. In these endings, the protection of one's king is of paramount importance: if the king is not protected, a player can be repeatedly placed in check by the opposing queen. In Queen and pawn endings a "passed" pawn, or a pawn which cannot be stopped by other pawns, can be extremely powerful. The player that has passed his pawn can force the enemy queen away, because if the queens are traded, the only piece left to stop the advance of the pawn is the opposing king.