Chess/Algebraic notation

Algebraic notation is used to record and describe the moves in a game of chess. It is now standard among all chess organizations and most books, magazines, and newspapers.

Naming squares on the board

Each square of the chessboard is identified with a unique pair of a letter and a number. The vertical files are labeled a through h, from White's left to White's right. Similarly, the horizontal ranks are numbered from 1 to 8, starting from White's home rank. Each square of the board, then, is uniquely identified by its file letter and rank number. The white king, for example, starts the game on square e1. The black knight on b8 can move to a6 and c6. Chess notations are a way to determine any unique point on the board.

Naming the pieces

Each type of piece (other than pawns) is identified by an uppercase letter, usually the first letter in the name of that piece in whatever language is spoken by the player recording.

K for king

Q for queen

R for rook

B for bishop

N for knight (since K is already used).

Pawns are not indicated by a letter, but by the absence of such a letter—it is not necessary to distinguish between pawns for normal moves, as only one pawn can move to any one square.

Notation for moves

Each move of a piece is indicated by the piece's letter, plus the coordinate of the destination square. For example Be5 (move a bishop to e5), Nf3 (move a knight to f3), c5 (move a pawn to c5—no initial in the case of pawn moves).

Notation for captures

When a piece makes a capture, an x is inserted between the initial and the destination square. For example, Bxe5 (bishop captures the piece on e5). When a pawn makes a capture, the file from which the pawn departed is used in place of a piece initial. For example, exd5 (pawn on the e-file captures the piece on d5).

Disambiguating moves

If two (or more) identical pieces can move to the same square, the piece's initial is followed by (in descending order of preference):

the file of departure if they differ;
the rank of departure if the files are the same but the ranks differ;
both the file and rank if neither alone uniquely defines the piece (after a pawn promotion, if three or more of the same piece are able to reach the square).

For example:

With two knights on g1 and d2, either of which might move to f3, the move is indicated as Ngf3 or Ndf3, as appropriate.

With two knights on g5 and g1, the moves are N5f3 or N1f3.

With three knights on e1, g5, and g1, the moves are Nef3, N5f3, or Ng1f3.

As above, an x may be used to indicate a capture: for example, Nexf3, N5xf3, and Ng1xf3.

Pawn promotion

If a pawn moves to its last rank, achieving promotion, the piece chosen is indicated after the move, for example f8Q, f8B, or f8(Q). The use of f8=Q is discouraged for technical reasons.

Castling

Castling is indicated by the special notations O-O (or 0-0) for kingside castling and O-O-O (or 0-0-0) for queenside castling.

Check and checkmate

A move which places the opponent's king in check usually has the notation "+" added.

Double check is sometimes represented "++".

Checkmate can likewise be indicated "#" (some use "++" or "mate" instead).

End of game

The notation 1-0 at the end of the moves indicates that white won, 0-1 indicates that black won, and ½-½ indicates a draw. Often there is no special indication of how a player won (other than checkmate, see above), so simply "1-0" or "0-1" may be written to show that one player resigned. Sometimes the word "Resigns" (or "White resigns" or "Black resigns" as appropriate) is used to show this.

Example

1.e4 e5 2.Nf3 Nc6 3.Bb5 Nf6 4.O-O. Moves may be interspersed with text. When the score resumes with a black move, an ellipsis (...) takes the place of the white move, for example:

1.e4 e5

2.Nf3

Black now defends his pawn

2...Nc6

3.Bb5 Nf6

4.O-O

An ellipsis is also used when a score starts with a Black move (when the score is not of a complete game but starts from a diagrammed position). However, helpmates usually use an opposite convention; Black moves first by default and White moves are indicated with an ellipsis if no Black move precedes.

Please note: There is no space between the period and the term. When correct algebraic notation is used, a .txt file may be renamed with the .pgn extension to create a working .pgn file that can be loaded by any modern chess program that reads .pgn files.

Common shorthand notation

Regarding specific moves

The following short-hand notations are sometimes used to comment single moves:

!	A good move
!!	An excellent move
?	A mistake
??	A blunder
!?	An interesting move that may not be best
?!	A dubious move, but not easily refuted
TN	A theoretical novelty

Regarding specific positions

The following short-hand notations are sometimes used to describe the annotator's view of the balance of strength between White and Black, in respect to a specific position on the board:

∞	Unclear. It is unclear who (if anyone) has an advantage. This is often used when a position is highly asymmetrical, such as Black having a ruined pawn structure but dangerous active piece-play.
=/∞	With compensation. This symbol indicates that whoever is down in material has compensation for the material.
=	Even position. This symbol indicates that the annotator believes that White and Black have equal chances.
+/=	Slight advantage. This symbol indicates that White has slightly better chances. In a similar way, if Black has the slightly better position it is reversed: =/+
+/−	Advantage. This symbol indicates that White has much better chances. If instead this is the case for Black, it is reversed: −/+ Also, it is often written as ± for White advantage, ∓ for Black advantage; the other similar symbols can be written in that style too.
+−	Decisive advantage. This symbol indicates that White has a winning advantage. It is reversed if Black has the winning position: −+

Future reading

This page covers algebraic notation use on Wikibooks, for a detailed general usage see Wikipedia's Algebraic notation.

References

Official FIDE rules on algebraic notation (see E. Miscellaneous / 01. Laws of Chess / Appendix C)