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 "!!". 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: for example, 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 may also 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". Evaluation symbols. Moves. Move evaluation symbols, by increasing effectiveness of the move: Section::::?? (Blunder). The double question mark "??" indicates a blunder, a 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. Blunders occur at all levels of play to all human competitors. Section::::? (Mistake). A single question mark "?" after a move indicates that the annotator thinks that the move is a poor one and that it should  not have been played. Mistakes often lead to loss of tempo or material. 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. 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. Section::::?! (Dubious move). This symbol is similar to the "!?" (below) but 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 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 they play well may receive a "?!". Alternatively, this may denote a move that is objectively bad but sets up an attractive trap. Section::::!? (Interesting move). 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. 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. Section::::! (Good move). An exclamation point ("!") indicates a good move—especially one which 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 widely between annotators; among them are strong , well-timed breakthroughs, sound sacrifices, moves that set traps in lost positions, moves that avoid such traps, and good psychological choices in the opening. Section::::!! (Brilliant move). 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. 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 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. 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 which he considered inferior but which he did not wish to comment on further; Simon Webb used it to indicate a move which is objectively sound, but was in his opinion a poor psychological choice; and Robert Hübner (see below) used it to indicate a move which 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.