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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 "!!". In these cases, the corresponding symbol is juxtaposed in the text immediately after 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. Moreover, an annotator's use of symbols is often influenced by the player's strength: a positional misjudgment that an annotator might give a "??" if played by a strong grandmaster might pass unremarked if played by a beginner.
Annotators' use of punctuation also may possibly be influenced by the result of the game regardless of the actual quality of the move; this tendency is sometimes referred to as "annotation by result".
|This article uses algebraic notation to describe chess moves.|
Move evaluation symbols, by increasing effectiveness of the move:
The double question mark "??" indicates a blunder, a very bad mistake. Typical moves which receive double question marks are those that overlook a tactic that wins substantial material or overlook a checkmate. A "??"-worthy move usually results in an immediately lost position. Occasionally, the sign is used for a move which transforms a won position into a draw, perhaps because the annotator feels that the mistake is unworthy of the player's skill level. They occur at all levels of play to all human competitors.
A single question mark "?" after a move indicates that the annotator thinks that the move is a poor one that should not be played. These often lead to loss of tempo or material. The nature of the 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.
Whether a single or double question mark is used is subjective and may depend on the player's strength. For instance, if a beginner makes a serious strategic error (for instance, accepting gratuitous pawn weaknesses or exchanging into a lost endgame) or overlooks a tactical sequence, this might be explained by the beginner's lack of skill, and be given only one question mark. If a master were to make the same move, some annotators might use the double question mark to indicate that one would never expect a player of the master's strength to make such a weak move.
This symbol is similar to the "!?" (below) but usually indicates that the annotator believes the move to be objectively bad, albeit hard to refute. The "?!" may also indicate that the annotator believes the move is deserving of criticism but not bad enough to warrant a "?". A sacrifice leading to a dangerous attack which the opponent should be able to defend against if he plays well may receive a "?!". Alternatively, this may denote a move that is objectively bad, but sets up an attractive trap.
The "!?" is one of the more controversial symbols. Different books have slightly varying definitions. Among the definitions are "interesting, but perhaps not the best move", "move deserving attention", "enterprising move" and "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 which might turn out to be strategically deficient.
While question marks indicate bad moves, exclamation points ("!") indicate good moves—especially ones which are surprising or involve particular skill. Hence annotators are usually somewhat conservative with the use of this symbol.
Once the players start making good choices when faced with difficult decisions, however, a few moves may receive exclamation points from annotators. Typical moves receiving exclamation points are strong , well-timed breakthroughs, sound sacrifices, and moves that avoid falling into traps.
The double exclamation point ("‼") is used for very strong moves such as 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, 13-year-old Bobby Fischer's decision to sacrifice his queen for a strategic attack was awarded by annotators a double exclamation point. 
A few writers have used three or more exclamation points ("!!!") for an exceptionally brilliant move. For example, in 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 general consensus among chess writers is that these symbols are unnecessary.
A few writers have used unusual combinations of question marks and exclamation points (e.g. "!!?", "?!?", "??!") for particularly unusual or controversial moves, but these have no generally accepted meaning, and are typically used for humorous or entertainment purposes.
Occasionally an annotation symbol may be put in parentheses, e.g. "(?)", "(!)". Different writers have used these in different ways; for example Simon Webb used "(?)" to indicate a move which is objectively sound, but was in his opinion a poor psychological choice, while Robert Hübner (see below) used it to indicate a move which is inaccurate and makes the player's task more difficult.
There are some systems which use these symbols in different ways.
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...".
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."
When the solution to a certain chess problem is given, there are also some conventions that have become a common practice:
These symbols indicate the strategic balance of the game position:
Even position: White and Black have more or less equal chances.
Slight advantage: White has slightly better chances.
Slight advantage: Black has slightly better chances.
Clear advantage: White has much better chances. It is also written as ±; the other similar symbols can be written in this style as well.
Clear advantage: Black has much better chances. It is also written as ∓; the other similar symbols can be written in this style as well.
Decisive advantage: White has a winning advantage.
Decisive advantage: Black has a winning advantage.
Unclear position: It is unclear who (if anyone) has an advantage. Often used when a position is highly asymmetrical, e.g. Black has a ruined pawn structure but dangerous active piece-play.