Editing Chess (section)

===Movement===
White moves first, after which players alternate turns. One piece is moved per turn (except when [[castling]], during which two pieces are moved). In the diagrams, dots mark the squares to which each type of piece can move if unoccupied by friendly pieces and there are no intervening piece(s) of either color (except the knight, which leaps over any intervening pieces). With the sole exception of ''[[en passant]]'', a piece captures an enemy piece by moving to the square it occupies, removing it from play and taking its place. The pawn is the only piece that does not capture the way it moves, and it is the only piece that moves and captures in only one direction (forwards from the player's perspective). A piece is said to ''control'' empty squares on which it could capture, ''attack'' squares with enemy pieces it could capture, and ''defend'' squares with pieces of the same color on which it could recapture. Moving is compulsory; a player may not skip a turn, even when [[zugzwang|having to move is detrimental]].

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{{Chess diagram  
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|Moves of the king
|  |  |  |  |  |  |  |
|  |  |  |  |  |  |  |
|  |  |  |  |oo|oo|oo|
|  |  |  |  |oo|kl|oo|
|  |  |  |  |oo|oo|oo|
|  |  |  |  |  |  |  |
|  |  |  |  |  |  |  |
|  |  |  |  |  |  |  | 
}}
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{{Chess diagram  
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|Moves of a rook
|  |  |  |oo|  |  |  | 
|  |  |  |oo|  |  |  | 
|  |  |  |oo|  |  |  | 
|oo|oo|oo|rl|oo|oo|oo|oo
|  |  |  |oo|  |  |  | 
|  |  |  |oo|  |  |  | 
|  |  |  |oo|  |  |  | 
|  |  |  |oo|  |  |  | 
}}
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{{Chess diagram  
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|Moves of a bishop
|  |  |  |  |  |  |  |oo
|oo|  |  |  |  |  |oo|
|  |oo|  |  |  |oo|  |
|  |  |oo|  |oo|  |  |
|  |  |  |bl|  |  |  |
|  |  |oo|  |oo|  |  |
|  |oo|  |  |  |oo|  |
|oo|  |  |  |  |  |oo|
}}
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{{Chess diagram  
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|Moves of a queen
|  |  |  |oo|  |  |  |oo
|oo|  |  |oo|  |  |oo| 
|  |oo|  |oo|  |oo|  | 
|  |  |oo|oo|oo|  |  | 
|oo|oo|oo|ql|oo|oo|oo|oo
|  |  |oo|oo|oo|  |  | 
|  |oo|  |oo|  |oo|  | 
|oo|  |  |oo|  |  |oo| 
}}
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{{Chess diagram 
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|Moves of a knight
|  |  |  |  |  |  |  | 
|  |  |oo|  |oo|  |  | 
|  |oo|  |  |  |oo|  | 
|  |  |  |nl|  |  |  | 
|  |oo|  |  |  |oo|  | 
|  |  |oo|  |oo|  |  | 
|  |  |  |  |  |  |  | 
|  |  |  |  |  |  |  | 
}}
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{{Chess diagram  
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|Moves of a pawn
|  |  |  |  |  |  |  |
|  |ox|oo|ox|  |  |pd|
|  |  |pl|  |  |xx|xo|xx
|  |  |  |  |  |  |xo| 
|  |oo|  |  |  |  |  |
|ox|oo|ox|  |  |pd|  |
|  |pl|  |  |xx|xo|xx|
|  |  |  |  |  |  |  | 
}}
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* The [[king (chess)|king]] moves one square in any direction. There is also a special move called ''[[#Castling|castling]]'' which moves the king and a rook. The king is the most valuable piece—it is illegal to play any move that puts one's king under attack by an opponent piece. A move that attacks the king must be parried immediately; if this cannot be done, the game is lost. (See {{seclink|#Check and checkmate}}.)
* A [[rook (chess)|rook]] can move any number of squares along a rank or file. A rook is involved in the king's castling move.
* A [[bishop (chess)|bishop]] can move any number of squares diagonally.
* A [[queen (chess)|queen]] combines the power of a rook and bishop and can move any number of squares along a rank, file, or diagonal.
* A [[knight (chess)|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 (chess)|pawn]] can move forward to the unoccupied square immediately in front of it on the same file, or on its first move it can optionally advance two squares along the same file, provided both squares are unoccupied (diagram dots). A pawn can capture an opponent's piece on a square diagonally in front of it by moving to that square (diagram crosses). It {{em|cannot}} capture a piece while advancing along the same file, nor can it move to either square diagonally in front without capturing. Pawns have two special moves: the [[#Special pawn moves|''en passant'' capture]] and [[#Special pawn moves|promotion]].
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====Check and checkmate====
{{Main|Check (chess)|l1=Check|Checkmate}}
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{{Chess diagram small 
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|
|  |  |  |  |  |  |  |
|  |  |  |  |  |  |  |
|  |  |kd|  |  |  |  |
|  |  |  |  |  |  |  |
|  |  |  |  |  |  |  |
|  |  |  |  |  |  |  |
|  |  |rl|  |  |  |  |
|  |  |  |  |kl|  |  |
|The black king is in [[Check (chess)|check]] by the rook.
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{{Chess diagram small  
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|
|  |  |  |  |  |  |  |
|  |  |  |  |  |  |  |
|  |  |  |  |  |  |  |
|  |  |  |  |  |  |  |
|  |  |  |  |  |  |  |
|  |  |  |  |bd|bd|  |kd
|  |  |  |  |  |  |  |
|  |  |  |  |  |  |  |kl
|White is in [[checkmate]], being unable to escape attack by the bishop on f3.
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When a king is under immediate attack, it is ''in [[Check (chess)|check]]''. A move in response to a check is legal only if it results in a position in which the king is no longer in check. There are three ways to counter a check:
* Capture the checking piece.
* Interpose a piece between the checking piece and the king (possible only if the attacking piece is a queen, rook, or bishop and there is a square between it and the king).
* Move the king to a square where it is not under attack.

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 get it out of check. In casual games, it is common to announce "check" when putting the opponent's king in check, but this is not required by the rules of chess and is usually not done in tournaments.<ref>{{Cite book|last=United States Chess Federation.|title=U.S. Chess Federation's official rules of chess|others=Just, Tim., Burg, Daniel B.|year=2003|isbn=0-8129-3559-4|edition=5th|publisher=Random House Puzzles and Games|location=New York|oclc=52859422}}</ref>

====Castling====
{{Main|Castling}}
[[File:ChessCastlingMovie en.svg|thumb|upright=0.95|Examples of [[castling]] ([https://upload.wikimedia.org/wikipedia/commons/5/55/ChessCastlingMovie_en.svg view animation])]]
Kings can ''castle'' once per game. Castling consists of moving the king two squares toward either rook of the same color, and then placing the rook on the square that the king crossed.

Castling is possible only if the following conditions are met:<ref name="FideLawsOfChess"/>
* Neither the king nor the rook has previously moved during the game.
* There are no pieces between the king and the rook.
* The king is not in [[#Check|check]] and does not pass through or finish on a square controlled by an enemy piece.

Castling is still permitted if the rook is under attack, or if the rook crosses an attacked square. 
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====Special pawn moves====
{{Anchor|en passant}}
{{Main|En passant|Promotion (chess)|l2=Promotion}}
[[File:ChessPawnSpecialMoves.gif|thumb|right|upright=1.15|Examples of special pawn moves: ({{em|left}}) [[Promotion (chess)|promotion]]; ({{em|right}}) ''[[en passant]]'']]
Pawns have two special moves:
* ''En passant'': when a pawn makes a two-square advance to the same rank as an opponent's pawn on an adjacent file, that pawn can capture it ''en passant'' ("in passing"), moving to one square behind the captured pawn. A pawn can only be captured ''en passant'' on the turn after it makes a two-square advance. In the animated diagram, the black pawn advances two squares from g7 to g5, and the white pawn on f5 takes it ''en passant'', landing on g6.
* ''Promotion'': when a pawn advances to its {{chessgloss|eighth rank|last rank}}, it is ''promoted'' and replaced with the player's choice of a queen, rook, bishop, or knight. Usually, pawns are promoted to queens; choosing another piece is called [[underpromotion]]. In the animated diagram, the c7-pawn is advanced to c8 and promoted to a queen. If the required piece is not available (e.g. a second queen), an inverted rook is sometimes used as a substitute, but this is not recognized in FIDE-sanctioned games.
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