Chess is played on a square board of eight rows called ranks, denoted 1 to 8 and eight columns called files, denoted a to h. The 64 squares alternate in colour and are referred to as light and dark squares.
By convention, the game pieces are divided into white and black sets, and the players are referred to as White and Black, respectively. Each player begins the game with 16 pieces of the specified colour, consisting of one king, one queen, two rooks, two bishops, two knights, and eight pawns. The pieces are set out as shown in the diagram and photo, with each queen on a square of its own colour (the white queen on a light square and the black queen on a dark square).
The white piece moves first. After the first move, players alternate turns, moving one piece per turn (except for castling, when two pieces are moved). Pieces are moved to either an unoccupied square or one occupied by an opponent's piece, which is captured and removed from play. With the sole exception of en passant, all pieces capture by moving to the square that the opponent's piece occupies. A player may not make any move that would put or leave the player's own king under attack. A player cannot 'pass' a turn. The player must make a legal move.
Each piece has its own way of moving. In the diagrams, the dots mark the squares to which the piece can move if there are no intervening piece(s) of either colour (except the knight, which leaps over any intervening pieces).
Moves of a king.
Moves of a queen.
Moves of a Rook.
Moves of a Horse/Knight.
Moves of a Bishop.
Moves of a Pawn.
The king moves one square in any direction. The king also has a special move called castling that involves also moving a rook.
A rook can move any number of squares along a rank or file, but cannot leap over other pieces. Along with the king, a rook is involved during the king's castling move.
A bishop can move any number of squares diagonally, but cannot leap over other pieces.
The queen combines the power of a rook and bishop and can move any number of squares along a rank, file, or diagonal, but cannot leap over other pieces.
A knight moves to any of the closest squares that are not on the same rank, file, or diagonal. (Thus the move forms an 'L'-shape: two squares vertically and one square horizontally, or two squares horizontally and one square vertically.) The knight is the only piece that can leap over other pieces.
A pawn can move forward to the unoccupied square immediately in front of it on the same file, or on its first move it can advance two squares along the same file, provided both squares are unoccupied (black dots in the diagram) or the pawn can capture an opponent's piece on a square diagonally in front of it on an adjacent file, by moving to that square (black 'x's). A pawn has two special moves: the en passant capture and promotion.
Initial position of kings and rooks. Kings may be moved to the indicated squares.
Castling is a move in the game of chess involving a player's king and either of the player's original rooks. It is the only move in chess in which a player moves two pieces in the same move, and it is the only move aside from the knight's move where a piece can be said to 'jump over' another.
Castling consists of moving the king two squares towards a rook on the player's first rank, then moving the rook to the square over which the king crossed. Castling may only be done if the king has never moved, the rook involved has never moved, the squares between the king and the rook involved are unoccupied, the king is not in check, and the king does not cross over or end on a square attacked by an enemy piece. Castling is one of the rules of chess and is technically a king move.
The notation for castling, in both the descriptive and the algebraic systems, is 0-0 with the kingside rook and 0-0-0 with the queenside rook. Castling on the kingside is sometimes called castling short and castling on the queenside is called castling long depending on whether the rook moves a short distance (two squares) or a long distance (three squares).
En passant and Promotion.
When a pawn makes a two-step advance from its starting position and there is an opponent's pawn on a square next to the destination square on an adjacent file, then the opponent's pawn can capture it en passant ('in passing'), moving to the square the pawn passed over. This can only be done on the very next turn, otherwise the right to do so is forfeited. For example, in the animated diagram, the black pawn advances two steps from g7 to g5, and the white pawn on f5 can take it en passant on g6 (but only on White's next move).
When a pawn advances to the eighth rank, as a part of the move it is promoted and must be exchanged for the player's choice of queen, rook, bishop, or knight of the same colour. Usually, the pawn is chosen to be promoted to a queen, but in some cases another piece is chosen. This is called under promotion. In the animated diagram, the pawn on c7 can be advanced to the eighth rank and be promoted. There is no restriction placed on the piece promoted to, so it is possible to have more pieces of the same type than at the start of the game (e.g., two or more queens).
The black king is in check by the rook.
When a king is under immediate attack by one or two of the opponent's pieces, it is said to be in check. A move in response to a check is legal only if it results in a position where the king is no longer in check. This can involve capturing the checking piece. Interposing a piece between the checking piece and the king (which is possible only if the attacking piece is a queen, rook, or bishop and there is a square between it and the king), or moving the king to a square where it is not under attack. Castling is not permitted when in check.
The object of the game is to checkmate the opponent. This occurs when the opponent's king is in check, and there is no legal way to remove it from attack. It is never legal for a player to make a move that puts or leaves the player's own king in check.
White is in checkmate, being unable to escape attack by the black bishops.
White is in checkmate, being unable to escape attack by the black bishops. a game can be won in the following ways:
The player whose turn it is to move is in check and has no legal move to escape check.
Resignation: Either player may resign, conceding the game to the opponent. It is usually considered poor etiquette to play on in a hopeless position, and for this reason high-level games rarely end in checkmate.
Win on time: In games with a time control, a player wins if the opponent runs out of time, even if the opponent has a superior position, as long as the player has a theoretical possibility to checkmate the opponent.
Black is not in check and has no legal move. The result is stalemate.
There are several ways games can end in a draw:
- Draw by agreement: Draws are most commonly reached by mutual agreement between the players. Traditionally, players have been allowed to agree to a draw at any point in the game.
- Stalemate: The player whose turn it is to move has no legal move and is not in check.
- Threefold repetition of position: This most commonly occurs when neither side is able to avoid repeating moves without incurring a disadvantage. In this situation, either player can claim a draw. This requires the players to keep a valid written record of the game so that the claim can be verified by the arbiter if challenged. The three occurrences of the position need not occur on consecutive moves for a claim to be valid. Currently this feature is not in our client software.
Fivefold and seventy-five-move rule are not used at this website.
Insufficient material: If neither player has a theoretical possibility to checkmate the opponent. For example, if a player has only the king and a knight left, and the opponent has only the king left, checkmate is impossible and the game is drawn by this rule. On the other hand, if both players have a king and a knight left, there is a highly unlikely yet theoretical possibility of checkmate, so this rule will not apply.
Draw on time: In games with a time control, the game is drawn if a player is out of time and the opponent has no theoretical possibility to checkmate the player. Not currently a rule at this website.
Time control: When online, chess games are played with a time control. If a player's time runs out before the game is completed, the game is automatically lost (provided the opponent has enough pieces left to deliver checkmate).