+

The + sign at the end of a move states an objective fact: after the move, the opposing king is under attack. If the position is not mate, the next legal move must remove the check by moving the king, capturing the attacker, or placing a piece in the attacking line when that line can be blocked.

In the standard form of algebraic notation, called Standard Algebraic Notation (SAN), Qe3+ means that the queen moves to e3 and gives check; Q is SAN's letter for a queen. The sign comes at the end of the move, after any capture or promotion information. Promotion is the conversion of a pawn that reaches the opposite edge of the board.

In Portable Game Notation (PGN), the plain-text format for game files, + is part of the standard move spelling. On a tournament scoresheet governed by the International Chess Federation (FIDE), it is optional. A double check, in which two pieces attack the king at once, does not receive a different sign in SAN; it is still written with +.