Chess is a turn-based board game for two players, and is one of the most popular games in the world. The goal of the game is to place the opposing king into checkmate, that is, a position in which the king is under attack but cannot escape. The game used to be treated as a status symbol of education and aristocracy.
Modern international chess has a powerful, sweeping queen who was not a piece provided in the original game. The long reach of bishops today was also lacking at first. Maneuvers such as castling or capturing en passant have been developed within the past few hundred years.
Today, chess is one of the most popular board games in the world. International competitions, including world championship events, are organized by an organization called FIDE and American competition organized by the USCF (United States Chess Federation). The only American world champion was Bobby Fischer, although Paul Morphy of Louisiana was likely the strongest player in the world in the 1850s, before a formal world champion was determined. The current World Chess Champion is Indian Viswanathan "Vishy" Anand.
- 1 Origins
- 2 The Board
- 3 Pieces
- 4 Gameplay
- 5 Notation
- 6 Tactics and strategy
- 7 Chess Variants
- 8 Computer Chess
- 9 External links
- 10 References
Chess has its roots in India, where a game called Shaturanga was played. The earliest extant description of the game is contained in the Bhavishya Purana, which dates from A.D. 300 to A.D. 600. Shaturanga used dice, but Hinduism bans gambling. As a result, the game of chess developed free from any dice or chance. The exact rules of Shaturanga are not known, but the game developed further in Persia into something very like its modern form. The Persian game Shatranj - which remains popular in the middle east today - is nearly identical to modern chess. By A.D. 1200 the game reached southern Europe, and in the late fifteenth century the Europeans adopted a number of changes: the queen, which had formerly been a very weak piece, became the strongest piece on the board, and allowing pawns to move two squares on the first move became standard. These changes had the effect of speeding up play, and they brought the game into the form we know today.
There has been some speculation that chess has roots in China. It's clear that chess is in some way related to XiangQi (Chinese Chess) and Shogi (Japanese Chess), but scholars disagree about whether either of these variants predates Shaturanga.
The chess board is a square, divided into 64 smaller squares arranged in eight rows of eight. The squares are alternating light and dark, with a light square in the bottom right hand corner.
The horizontal rows of squares are referred to as "ranks" and the vertical rows are referred to as "files".
Each player has a total of 16 pieces; 8 pawns, 2 knights, 2 bishops, 2 rooks, 1 queen, and 1 king.
Relative Value of Pieces
There are several different ideas about the relative value of the pieces. It is important to note that the "points" used to assign a value to each piece are hypothetical and do not constitute a score; they are merely an attempt to quantify the relative power that each piece can hypothetically exert upon the board.
The method most often used is:
- Knight--3 (some say 2.5, as Knights are generally regarded as slightly inferior to Bishops in many middlegame and endgame situations)
- King--Priceless, since its loss means the loss of the game. However, as an active piece in the endgame it is usually considered to have a value of 3.
(The value to the player of some pieces will actually vary during the course of the game, for instance, in an endgame, the King has an attacking power of about 3)
The most popular style of pieces are known as Staunton style pieces, the tournament standard for chess pieces, although other types exist. Often, popular themed chess sets will appear with characters from popular culture or fiction taking the places of the more common Staunton style pieces. These novelty pieces are not tournament sanctioned however, and can sometimes cause confusion during game play as to which piece is which.
Although chess pieces can come in a variety of materials, marble and glass tend to be very popular, but for most chess tournaments, simple plastic pieces are usually favored. Also, while many home chess sets use heavy boards made out of wood or stone or some polymer material, tournament boards are actually roll-able mats with the board printed on it.
The object of the game is to checkmate the other player's King before he checkmates your king. When a pawn reaches the far side of the board, it may be promoted to any other piece (except a King).
- The players alternate moving until the game has ended.
- The player with the White pieces always moves first.
The pieces are put on the board in each player's side as follows:
- In the first row from left to right (with the leftmost square being black): rook, knight, bishop, queen, king, bishop, knight and rook.
- The second row is filled with pawns.
The pieces move as follows.
- The pawn moves one square forward, except when moving from its opening position, when it can optionally move two. The pawn is the only piece that captures in a way different from the way it moves. It captures opposing pieces by capturing one square diagonally forward. When another piece is on the square directly in front of a pawn it cannot move unless it is making a capture.
- The knight, which is the only piece that can jump over other pieces, moves one square in one straight direction and two in the other.
- The bishop can move as many squares as desired diagonally.
- The rook can move as many squares as desired in a straight direction.
- The queen is the most powerful piece in the board. It can move as many squares as desired (without jumping over another piece), either straight or diagonally.
- The king, which is the most important piece on the board, moves one square, either straight or diagonally.
All pieces except for the pawn capture along their lines of motion. A capture is made by moving a piece to a square occupied by one of the opponent's pieces, and removing the opponent's piece from the board. If a piece can move to occupy the location of an opponent's piece, it can capture that piece. The pawn, can only capture by moving diagonally forward one square. A piece is said to be undefended if it has no piece "supporting" its position - i.e., preventing an opponent from capturing it by threat of losing his attacking piece.
- Castling- When a player has no pieces between a rook and his king, and he has not moved either piece, he can move the king two squares in the direction of the rook, and then place the rook on the square that the king passed over. A player cannot castle if the King is currently in check, would be in check after castling, or would move through a square which is under attack.
- en passant- French for "In passing." In chess, if a player pushes his pawn far down to the end of the board, and his opponent pushes a starting pawn 2 spaces ahead, to put the pawn on the same row to avoid confrontation, the player may choose to invoke the "en passant" move, which treats the enemy pawn as though it had only moved one space. The player may capture diagonally on the square behind the enemy pawn, and remove the enemy pawn. The principle is that the two space rule for a pawn's first move cannot be used to avoid confrontation between two pawns. However, the player may only invoke "en passant" on the first turn after the opponent pushes his pawn. He cannot make it after that turn.
The end of the game
A chess game may end in a number of ways.
- Checkmate: The winning player checkmates his opponent's King (see below).
- Resignation: The losing player, facing an inevitable future checkmate, resigns rather than play out an extended series of hopeless moves. A player may indicate resignation by toppling his king on its side.
- Loss on Time: In games with a time limit, a player may lose by failing to make a time control, causing his clock to run out.
- Draw: The game may end in a draw, in which case neither player wins.
Checkmate is achieved when the following conditions are met.
- The King is in check; that is, it is directly attacked by an opponent's piece.
- Every square that the King can move to is also attacked by an opponent's piece.
- The Piece that is attacking the King cannot be captured.
- Another Piece cannot be interposed between the attacking piece and the King to block the check.
When a King is checkmated, the game is over, and the player initiating the checkmate is the winner.
There are several ways that the game can end in a draw.
- Stalemate: A player is said to be stalemated when he cannot make a legal move, and is not in check.
- Draw by agreement: The players mutually agree to a draw. In competitive chess, a player may make a draw offer after he has made his move, but before he has started his opponent's clock.
- Draw by repetition: Either player may claim a draw if the same position has appeared on the board three times. The three occasions need not be consecutive.
- 50 move rule: Either player may claim a draw if fifty moves have transpired without a capture or a pawn move.
Chess notation is used to record the moves of a chess game. This has several uses. Notation can be used to record games for review at a later time. There are two major methods of chess notation, Algebraic and Descriptive.
For all forms of Notation
The notation for a chess game is taken like this. At the top of the page are the players — white listed first — with their names under their colors. Numbers go down the left side of the page to indicate the move number. (see below)
Name Name 1.
Moves are recorded in columns, separated by commas.
Space is usually allotted on the top of tournament scoresheets to record the date and location of the game, and sometimes to record the time limit and opening name.
Each piece is designated by its corresponding letter as follows:
K = King
Q = Queen
R = Rook
B = Bishop
N = Knight (notice 'K' is reserved for the King)
P = Pawn
(In strict chess parlance, the pawns are not considered pieces; officially, a standard chess set consists of sixteen pieces and sixteen pawns.)
- Moves to x Captures + Check ++ Checkmate 0-0 Castles king-side 0-0-0 Castles queen-side e.p. en passant / to indicate which square a piece moved from (only when needed to clarify) /Q Pawn promotion. (use /Q for queen, /R for rook, etc.) ! A good move !! A very good move !? An interesting move ?! A dubious move ? A questionable move ?? A blunder
AlgebraicAlgebraic is the most commonly used method of notation.
In algebraic notation, each file is assigned a letter, and each rank is assigned a number. Each square is designated by the letter and number from it's rank and file. a1 is the square in the bottom left corner for the white player.
Moves are recorded by indicating the piece to be moved and the square it is to be moved to, sometimes using a hyphen (-). For example, if white wants to move his Kingside Knight towards the center of the board to start the game, the notation would be:
White Black 1. Nf3, ....
White Black 1. N-f3, ....
In algebraic notation, a P is not used to indicate the pawn. A pawn move is implied when no piece is indicated. So if white wants to advance his king pawn 2 squares, and black responds by advancing his king pawn 2 squares, the notation would be:
White Black 1. e4, e5, 2. ....
Occasionally, two pieces of the same type can move to the same square. To eliminate ambiguity, the unique rank or file of the moving piece is identified after the piece symbol. For example, suppose both of Black's Rooks are on the 8th rank (on the squares f8 and a8), and there are no pieces in between them. Black moves the f8 Rook to d8. In other circumstances, the move would be annotated
17. .... Rd8
but because either Rook could have moved to d8, the identifying file for the f8 Rook must be included, as in
17. .... Rfd8
Captures by a piece or pawn are indicated by first transcribing the symbol for the piece performing the capture, followed by an 'x', followed by the square the capturing piece or pawn moved to. For example, if White uses his Queen to capture a piece on the square h7 on move 23, the correct notation is
23. Qxh7, ....
Because pawns are not designated with a symbol, the system is slightly different for pawn captures. The file originally occupied by the pawn is used to identify the pawn performing the capture. If a black pawn on e5 captures a white piece or pawn on d4 on move 5, the notation is
5. ...., exd4
In the more archaic descriptive notation, squares are described according to the starting piece positions. The square originally occupied by the Rook on the Queenside is referred to as "Queen's Rook One" (QR1), while "Queen's Rook Four" is the square directly in front of the Queen's Rook on the fourth rank. Thus, a typical opening move is described as "Pawn to King Four", and is written as
1. P-K4, ....
Note that in descriptive notation, pawns have the designation 'P'. The notation's disadvantages become apparent over the course of a complex game, especially because the same square has different names depending on the perspective of the White and Black pieces. King's Bishop Three (KB3) for White is King's Bishop Six (KB6) for Black.
Captures in descriptive notation operate similar to algebraic notation; for example,
45. .... R-xQN7
means that on his 45th move, Black captured a piece or pawn on his Queen's Knight Seven square (the b2 square in algebraic notation).
Tactics and strategy
Chess players often refer to shorter, forcing sequences of moves that lead to clear advantages as tactics, while moves designed to create or nurture long-term advantages are called strategic.
Chess vs. Go
David Lai wrote on the difference between chess and go:
|“|| The philosophy behind chess is to win decisively. For the winner, victory is absolute, as is defeat for the loser. In chess, both players have the same clear and overriding objective―capturing the opposing king―and accomplish this objective by decimating whatever opposing forces are standing in the way. In go, total victory usually happens between two mismatched players. That kind of victory, as Sun Tzu puts it, is not the pinnacle of excellence. In a go game between two well-matched players, the margin between win and lose is usually very small, often decided by only a few points. The philosophy behind go therefore is to compete for relative gain rather than seeking complete annihilation of the opponent’s forces. It is dangerous to play go with the chess mindset. One can become overly aggressive so that he will stretch his force thin and expose his vulnerable parts in the battlefields.
In chess, the focus is on the king. All the moves are geared toward checking the king. In designs to capture the king, chess players always try to eliminate the powerful pieces such as the queen, knight, castle, and bishop. Chess players typically focus on these powerful military units as the ‘center of gravity’ and ‘decisive point’ (in Clausewitz and Jomini’s terms). Naturally, chess players are single-minded. In go, it is a war with multiple campaigns and battlefields. There is no one single focus on the board. A go player must always keep the whole situation in mind. Attacking the opponent’s strategy therefore is much more appropriate in go. As a prolonged and complex game, go players focus on building or creating rather than chess players’ emphases on removal and destruction.” 
Another major difference between chess and go is that in go matches there is a winner and a loser and there are no draw games.
There are a number of games based on chess with rule variations, and these are referred to as chess variants. One of the most popular of these is Bughouse, a partner-based game in which a player who captures his opponent's piece can give it to a partner on another board to drop on a square of his choosing. Another is Kriegspiel, a game in which a player can see his pieces but not that of his opponent.  A simpler variant is Antichess, which is also called Suicide chess, in which a player must make a capturing move if any legal captures exist on the board, and in which the goal is to run out of pieces first.
In 1996, Bobby Fischer introduced a variant called FischerRandom Chess, which involves scrambling the positions of the pieces on the first and eighth ranks before starting play. A number of rules govern the precise manner in which the pieces can be arranged; for example, the king must be somewhere between the two rooks, so that castling to either side is still possible, and the black and white positions must mirror one another. The rules provide for 960 possible starting positions, and for this reason the game is sometimes called Chess960. Fischer hoped his variant would encourage creative thinking and avoid the memorization associated with opening play in modern chess.
Deep Blue, a computer developed by IBM, was the first computer engine to beat a human world champion in 1997, when it defeated Garry Kasparov in a six game series. This series was a rematch of 1996 series which Kasparov won, although Deep Blue had been upgraded since the first series. It should be noted that during this second match, Deep Blue was also upgraded between games to avoid falling into the same type of trap more than once.
Chess engines have increased in strength in recent years to the point where humans are falling behind. In 2005, Michael Adams, one of the top fifteen players in the world, played a six game match against the engine Hydra, and lost five games with only one draw. Chess writer Eric Schiller, who uses computer assistance in writing his books, admits that "computers have taken some of the fun out of (chess)." Despite this, chess remains far from being a solved game.
- FIDE - World Chess Federation
- USCF - United States Chess Federation
- ICCF - International Correspondence Chess Federation
- ACP - Association of Chess Professionals
- FICS - Free Internet Chess Server
- [David Lai, “Learning From The Stones: A Go Approach To Mastering China’s Strategic Concept, Shi, pp. 28-29