# Algebraic Chess Notation

We use algebraic chess notation to represent chess positions without posting a full chessboard. This allows players to converse about chess positions clearly without a board in front of us.
Imagine the chess board as a 2D plot. Below is the table I made to explain this notation in my paper How Stockfish Works: An Evaluation of the Databases Behind the Top Open-Source Chess Engine. I will post more about this paper when I’ve finished editing it.

Symbol Meaning
a-h file from white’s left to right
1-8 rank from white to black
R, N, B/S, Q, K Rook, Knight, Bishop, Queen, King
x capture; the piece that was at this location is removed
+ a note that the king is threatened
# or ++ checkmate; a note that this is the reason for the end of the game
= promoted to; a pawn arriving at the opposite side of the board is promoted to another piece, often a queen.
0-0 castle on the kings side; move to positions (B – Kg8 Rf8 ; W – Kf1 Rg1) (if neither has moved before this point in the game)
0-0-0 castle on the queens side; (B – Kd8 Rc8 ; W – Kc1 Rd1) (if neither has moved before this point in the game)
e.p. en passant capture (non-SAN), a note that a pawn was taken by another pawn passing it. When a pawns first move is a two space move (from 7 to 5 for black or 2 to 4 for white) it can be captured by moving behind it to the 6th rank (white taking black) or 3rd rank (black taking white).
?, ??, !, !! editorial comments, weak, very weak, strong, very strong
 Coordinates in Algebraic Chess Notation
I encourage you to explore additional background information provided by the online book Building Skills in Python.