Chessy
What Do the Symbols in Chess Notation Mean?
Common symbols in chess notation are + for check, # for checkmate, x for a capture, O-O for kingside castling, and O-O-O for queenside castling.
Move symbols
These symbols describe what actually happened on the board. x marks a capture (Nxe5 means a knight captured on e5), + marks check, and # marks checkmate. O-O is kingside castling and O-O-O is queenside castling — the extra 'O' representing the longer distance the rook travels on that side.
Annotation symbols
Beyond describing the move itself, annotators add symbols to judge its quality. ! marks a strong move and !! a brilliant one; ? marks a mistake and ?? a blunder. The hybrid symbols !? (interesting, worth considering) and ?! (dubious, probably not great) flag moves that are harder to fully evaluate.
Reading a full move in notation
Put together, a notation entry like Qxh7#!! tells a complete story: the queen captured on h7, delivering checkmate, and the annotator considers it a brilliant move. Learning these symbols lets you follow any published game or engine analysis without needing a diagram for every move.
Frequently asked questions
What does + mean in chess notation?
It means the move puts the opponent's king in check.
What does # mean in chess notation?
It means the move is checkmate, ending the game.
What's the difference between O-O and O-O-O?
O-O is kingside castling; O-O-O is queenside castling, named for the longer rook move involved.
What do !? and ?! mean?
!? marks an interesting move worth considering, while ?! marks a dubious move that's probably not the best choice.