Chess, unlike many other games, does not involve direct chance such as the roll of a dice or which card is drawn. The outcome completely depends on the decisions of the players. However, because of its vast complexity, the far-reaching consequences of some decisions are practically unforeseeable.
One player ("White") has the white pieces while the other ("Black") has the black pieces. Sometimes the colors are not black and white (for instance, light and dark, or yellow and blue), but they generally contrast each other. In friendly games the choice of colors can be made by any method, such as flipping a coin. If there is no coin at hand, another typical way of deciding would be to conceal a black piece in one hand and a white piece in the other and ask one's opponent to select a hand. The colored piece selected will be the opponent's color. In competitive games the players are assigned their colors.
Order of play
Once all the pieces have been arranged, White (or the lighter color) makes the first move. White always makes the first move; this is important for notation, and any chess player will insist upon it. After White has made the move, Black will then make a move. The gameplay will continue in alternating fashion, White making a move, followed by Black.
General movement rules
- A move consists of moving a single piece, in accordance with its rules of movement, to a square that is unoccupied or occupied by an enemy piece. A player may never move a piece onto a square already occupied by another of his or her own pieces.
- Exception: There is a special move called "castling" where two pieces, a rook and the king, are moved; see below.
- If a piece is moved onto a square occupied by an enemy piece, the latter piece is removed from play and the first piece replaces it. The removed piece is said to have been captured or taken.
- Exception: In en passant capture, a pawn moves to an unoccupied square but still captures another pawn "in passing"; see below.
- Most pieces move and capture opponent pieces in the same way.
- Exception: The pawn has separate rules for moving and capturing opponent pieces.
- Most pieces may only make a move to a non-adjacent square if all the intervening squares are vacant (pieces may not 'jump over' other pieces).
- Exception: The knight can move to any suitable final square regardless of occupants of other squares.
- Exception: In castling, a king and a rook jump over each other.
- No player may make a move that leaves their king "in check" (see below).
- The player must always make a move when it is his or her turn. In other words, he or she cannot choose not to make a move. If no legal move is possible the game ends in a draw (see below), except when the king is in check - this is called checkmate, and is usually how the opposing player wins.
Also, when a pawn moves to a square at the opposite end of the board, it becomes a different piece (pawn promotion); all of these exceptions are covered below in more detail.
The board
Traditionally, the game is played on a board of 64 alternating black and white squares turned with a white square to each player's near right-hand corner. "White on right" is a helpful saying to remember this convention. The light and dark squares on the chessboard and the light and dark chess pieces are traditionally referred to as "white" and "black" respectively, although in modern chess sets almost any colors may be used (as long as they are not the same colors.)
The horizontal rows of squares are called ranks and are numbered 1-8; the vertical columns of squares are called files and given the letters a-h. This way any single square can be easily identified by its rank and file, making it possible to record games by writing down the starting and ending position of the piece that moves every turn.
A chess diagram is always printed from the White player's perspective.
 | a | b | c | d | e | f | g | h | |
| 8 |  | | | | | | | | 8 |
| 7 | | | | | | | | | 7 |
| 6 | | | | | | | | | 6 |
| 5 | | | | | | | | | 5 |
| 4 | | | | | | | | | 4 |
| 3 | | | | | | | | | 3 |
| 2 | | | | | | | | | 2 |
| 1 | | | | | | | | | 1 |
| a | b | c | d | e | f | g | h | |
The pieces
The movement of the individual pieces is described below. In all the board diagrams shown, the squares to which the piece in question can move are indicated with x's.
Pawn
Pawns can move one square straight forward, or optionally and on their first move only, two squares straight forward. The pawn is the only piece that can't move backwards.
Pawn move
Capturing PiecesThe pawn can move one square diagonally forward to capture a piece, but cannot capture a piece by moving straight forward. For this reason, two opposing pawns on a file may become blocked by each other. In the first diagram below, legal capture moves for the white pawn is indicated with black circles. To capture means to displace a piece, meaning, to replace the captured with the capturer. In the second diagram below the White pawn is prevented from moving forwards by the Black pawn immediately in front of it (in the d-file) which it cannot capture, but it can capture the adjacent Black pawn by moving diagonally forward as seen in the last diagram. The pawn is the only piece that moves and captures differently.
Pawn capture
Position before capture
Position after capture
Knight The knight has a unique move that allows it to flank the other pieces. The easiest way to describe this move is that he moves to a square of the opposite color from the one he's on that is exactly two squares away from him.
Knight move, When starting from a light colored square he moves to a dark square two away
Knight move, when starting from a dark colored square he moves to a light square two away
The knight moves along straight lines like all other pieces, two such lines marked here
Another way to visualize the move is this: of the 16 squares that are 2 away from a knight he reaches the 8 that are of the opposite color of the square he's on and the other 8 can be reached by a queen where she on his square.
Knight move compared to the queen move
Knight move compared to the queen again. Of the squares 2 away, the knight has 8 marked X and the queen could reach the other 8
It is important to remember that the knight moves in a straight line like all the other pieces, it's just along lines of movement no other piece uses. Consider this comparison: A queen moves ordinally along the ranks and files - North, East, South, and West on a compass rose; and she also moves diagonally - Northeast, Southeast, Southwest, and Northwest on a compass rose. The knight moves along the wind lines of the rose - North by Northeast, East by Northeast, and so on. These lines pass between the squares adjacent to the knight and pass through the middle of the squares that are one square away from the knight. The knight moves to the first square its line of movement passes through the middle of, so like the King the knight has eight squares he can move to when he is near the center of the board. Since the knight is moving between the squares adjacent to him pieces do not hinder his move whether they are allied or enemy. Capturing PiecesThe knight captures any opponent's piece that occupies a square it can move to by removing that piece from the board and placing the knight in that square. An important consequence of the knight's use of wind lines is that it can attack (that is, threaten to capture) pieces without being threatened in return so long as they are not also knights. The reverse is also true - pieces attacking a knight are never threatened by it.
Knight capture
Knight capture - Jumping over pieces
Bishop The bishop can move any number of squares diagonally. The bishop may not jump over any piece of either color. The bishop is restricted to the color of squares on which it began the game. Each player starts out with one light-square bishop that moves on the light colored squares, and one dark-square bishop that moves on the dark colored squares. In the diagram below, the bishop stands on a light square and can only move to other light squares.
Bishop move
Bishop capture
Capturing PiecesThe bishop captures any opponent's piece that it encounters during the movement described above, and then occupies the captured piece's square. In the diagram above the bishop may take any of the black queens. Notice that bishop may not move (jump) to squares behind or capture pieces hiding behind the queens. Rook The rook can be moved any number of squares horizontally or vertically, but not diagonally. Like the bishop, the rook cannot jump over any pieces, except for "castling".
Rook move
Rook capture
Capturing PiecesIf the rook attempts to occupy a space already occupied by an opponent's piece, it captures the piece. In the diagram above the rook may take any of the black queens. Queen The queen is the most powerful piece, being able to move any number of squares in any lateral or diagonal direction. It is best described as the combination of a rook's and bishop's movement capabilities.
Queen move
Queen capture
Capturing PiecesThe queen captures any opponent's piece that it encounters during the movement described above, and then occupies the captured piece's square. In the diagram above the queen may take any of the black queens. King The king can move one square at a time in any direction, as long as doing so does not place himself in check (see below).
King move
King capture
King capture
Capturing PiecesThe king may capture any opponent's piece adjacent to it, as long as doing so does not place himself in check (see below). In the diagrams above the king may take any of the black knights. CheckThe king is the most important piece belonging to each player, though not the most powerful. If a player moves a piece such that he threatens to capture his opponent's king in the next move, that king is said to be in check. If a player's king is in check, he must immediately remove the check by moving the king, blocking the check with another piece, or capturing the checking piece. In the diagram below black's rook has checked the white king. White may avoid the check by moving the king one step sideways, blocking the check by putting the rook between the attacking black rook and the white king, or capture the black rook using the white bishop. Other normally legal moves, like moving one of the pawns, are illegal in this position since they will not remove the check. In a friendly game a check is usually announced by saying check after the move is completed.
White king in check
CheckmateIf the king is placed in check and can not escape, it is said to have been checkmated (or "mated" for short). The first player to checkmate the opponent's king wins the game. Note that the king is never actually captured, since it is obliged to move out of check whenever possible (and the game ends when it is impossible). In the diagram below white has no options to escape the check from black's rook, he is therefore checkmated.
White king in checkmate
Special Restrictions — Avoiding "Self-check"Players may not make any move which allows their king to be captured in the next move, i.e. places their own king in check. Thus two kings may never occupy adjacent squares, since they would have put themselves in check by moving there. This is called the "opposition" and is indispensable when, for instance, you are using a queen or rook to checkmate a king. The White king in the following diagram cannot move upwards or to the left since it would be in check from the bishop, or diagonally downwards which would leave it adjacent to the Black king. Also, as no piece is threatening it if it fails to move, the king is not currently in check. Similarly, the Black king cannot move diagonally upwards as that would put it next to the White king.
King may not move to an attacked square
The diagram below shows a position where the white bishop's movement is restricted by the same rule; the bishop can not be moved since the move would let black capture the white king in his next move. The white king on the other hand may move to any of the adjacent squares.
Bishop may not move
Special MovesPawn PromotionIf a pawn makes it to one of the eight squares along the far edge of the board from their initial position, the pawn is "promoted". Upon reaching the far rank the player exchanges the pawn with either a queen, a rook, a bishop, or a knight. The player's move ends when the new piece occupies the promoted square. The new piece need not be a previously captured piece. Thus a player can have more than one queen, and more than two rooks, bishops or knights on the board. The player may never have more than one king, since the pawn can not be promoted to a king. In theory it is possible to get up to nine queens, or ten rooks, bishops or knights since there are eight pawns to promote. In practice however the pawn is usually promoted to a queen, since it is the most powerful piece, and it is rare for a player to have more than two queens on the board. If an extra queen is not at hand, a upside-down rook is usually used as a substitute.
Castling Kingside castling: O-O  Queenside castling: O-O-O Castling is a move involving the king and either of the rooks. Castling performed with the king's rook is called kingside castling, performed with the queen's rook is called queenside castling. A castling is typically done to move the king to a protective 'castle' surrounded by three pawns and a rook. Subject to restrictions detailed below, a player may move his king two squares towards the rook, and subsequently, on the same turn, move the rook adjacent to but on the opposite side of the king, (onto the square over which the king has just passed). The restrictions specific to castling are:
The diagrams below shows example of positions where castling is not legal.
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