Chess annotation symbols

When annotating chess games, commentators frequently use widely recognized annotation symbols. Question marks and exclamation points that denote a move as bad or good are ubiquitous in chess literature. Some publications intended for an international audience, such as the Chess Informant, have a wide range of additional symbols that transcend language barriers.

The common symbols for evaluating the merits of a move are "??", "?", "?!", "!?", "!", and "!!". The chosen symbol is appended to the text describing the move (e.g. Re7? or Kh1!?); see Algebraic chess notation.

Use of these annotation symbols is subjective, as different annotators use the same symbols differently.

Moves
Move evaluation symbols, by decreasing severity or increasing effectiveness of the move:

?? (Blunder) 
The double question mark "??" indicates a blunder, a critically bad mistake. Typical moves that receive double question marks are those that overlook a tactic that wins substantial or overlook a checkmate. A "??"-worthy move may result in an immediately lost position, turn a won position into a draw, lose an important piece or otherwise severely worsen the player's position. Though more common among less experienced players, blunders occur at all levels of play.

? (Mistake) 
A single question mark "?" indicates that the annotator thinks that the move is a mistake and should not have been played. Mistakes often lead to loss of tempo, material, or otherwise a worsening of the player's position. The nature of a mistake may be more strategic than tactical; in some cases, the move receiving a question mark may be one for which it is difficult to find a refutation. A move that overlooks a forthcoming brilliant combination from the opponent would rarely receive more than one question mark, for example.

?! (Dubious move) 
A question mark followed by an exclamation mark "?!" usually indicates that the annotator believes the move to be dubious or questionable but to possibly have merits. The "?!" may also indicate that the annotator believes the move is weak or deserving of criticism but not bad enough to warrant a "?". On certain Internet chess servers, such as Chess.com and Lichess, this kind of move is marked as an "inaccuracy", denoting a weak move, appearing more regularly than with most annotators. A sacrifice leading to a dangerous attack that the opponent should be able to defend against if they play well may receive a "?!". Alternatively, this may denote a move that is objectively bad but sets up an attractive trap.

!? (Interesting move) 
Similar to "?!" (see above), an exclamation mark followed by a question mark "!?" is one of the most controversial symbols. Different books have slightly varying definitions, such as "interesting, but perhaps not the best move", "move deserving attention", "speculative move", "enterprising move" or "risky move". Usually it indicates that the move leads to exciting or wild play but that the objective evaluation of the move is unclear. It is also often used when a player sets a cunning trap in a lost position. Typical moves receiving a "!?" are those involving speculative sacrifices or dangerous attacks that might turn out to be unsound.

Andrew Soltis jokingly called "!?" the symbol of the lazy annotator who finds a move interesting but cannot be bothered to work out whether it is good or bad.

! (Good move) 
An exclamation point "!" indicates a good move —especially one that is surprising or requires particular skill. The symbol may also be interpreted as "best move". Annotators are usually somewhat conservative with the use of this symbol.

Reasons for awarding the symbol vary greatly between annotators; among them are strong, good psychological opening choices, well-timed breakthroughs, sound sacrifices, moves that set traps in lost positions, moves that avoid such traps, moves that punish mistakes well, sequential moves during brilliancies, and being the only good move that maintains the player's position.

!! (Brilliant move)  
The double exclamation point "!!" is used for very strong moves, usually difficult-to-find moves which require a high level of skill and calculation. Typical moves that receive a double exclamation mark include sound sacrifices of large amounts of material and counter-intuitive moves that prove very powerful.

For example, in what is known as the Game of the Century, there are two moves by 13-year-old Bobby Fischer which annotators typically award a double exclamation point - 11...Na4!! and 17...Be6!!, knight and queen sacrifices respectively.

Others     
A few writers have used three or more exclamation points ("!!!") for exceptionally brilliant moves. For example, when annotating Rotlewi–Rubinstein 1907, Hans Kmoch awarded Rubinstein's 22...Rxc3!!! three exclamation points. Likewise, an exceptionally bad blunder may be awarded three or more question marks ("???"). The majority of chess writers and editors consider these symbols unnecessary.

A few writers have used unusual combinations of question marks and exclamation points (e.g. "!!?", "?!?", "??!") for particularly unusual, spectacular or controversial moves, but these have no generally accepted meaning and are typically used for humorous or entertainment purposes.

Sometimes annotation symbols are put in parentheses, e.g. "(?)", "(!)". Different writers have used these in different ways; for example, Ludek Pachman used "(?)" to indicate a move that he considered inferior but that he did not wish to comment on further; Simon Webb used it to indicate a move that is objectively sound, but was in his opinion a poor psychological choice; and Robert Hübner (see below) used it to indicate a move that is inaccurate and makes the player's task more difficult.

Alternative uses
Some writers take a less subjective or more formalized approach to these symbols.

Nunn's convention
In his 1992 book Secrets of Rook Endings and other books in the series (Secrets of Minor-Piece Endings and Secrets of Pawnless Endings), John Nunn uses these symbols in a more specific way in the context of endgames where the optimal line of play can be determined with certainty:

This convention has been used in some later works, such as Fundamental Chess Endings and Secrets of Pawn Endings by Karsten Müller and Frank Lamprecht, but it can be safely assumed the convention is not being used unless there is a specific note otherwise. The Nunn convention cannot be used to annotate full games because the exact evaluation of a position is generally impractical to compute.

In 1959, Euwe and Hooper made the same use of the question mark, "... a decisive error ...".

Hübner's approach
German grandmaster Robert Hübner prefers an even more specific and restrained use of move evaluation symbols: "I have attached question marks to the moves which change a winning position into a drawn game, or a drawn position into a losing one, according to my judgment; a move which changes a winning game into a losing one deserves two question marks ... I have distributed question marks in brackets to moves which are obviously inaccurate and significantly increase the difficulty of the player's task ... There are no exclamation marks, as they serve no useful purpose. The best move should be mentioned in the analysis in any case; an exclamation mark can only serve to indicate the personal excitement of the commentator."

Chess composition
When the solution to a certain chess problem is given, there are also some conventions that have become a common practice:

Positions
These symbols indicate the strategic balance of the game position:

Other symbols
There are other symbols used by various chess engines and publications, such as Chess Informant and Encyclopaedia of Chess Openings, when annotating moves or describing positions. Many of the symbols now have Unicode encodings, but quite a few still require a special chess font with appropriated characters.