Chess opening
The opening is the initial stage of a chess game. It usually consists of established theory. The other phases are the middlegame and the endgame. Many opening sequences, known as openings, have standard names such as "Sicilian Defense". The Oxford Companion to Chess lists 1,327 named openings and variants, and there are many others with varying degrees of common usage.
Opening moves that are considered standard are referred to as "book moves", or simply "book". When a game begins to deviate from known opening theory, the players are said to be "out of book". In some openings, book lines have been worked out for over 30 moves, such as some lines in the classical King's Indian Defense and in the Najdorf Variation of the Sicilian Defense.
Professional chess players spend years studying openings, and they continue doing so throughout their careers as opening theory continues to evolve. Players at the club level also study openings, but the importance of the opening phase is less there since games are rarely decided in the opening. The study of openings can become unbalanced if it is to the exclusion of tactical training and middlegame and endgame strategy.
A new sequence of moves in the opening is referred to as a theoretical novelty. When kept secret until used in a competitive game, it is often known as a prepared variation, a powerful weapon in top-class competition.
Aims of the opening
Common aims in opening play
Whether they are trying to gain the upper hand as White, or to as Black or to create dynamic imbalances, players generally devote a lot of attention in the opening stages to the following strategies:- Development: One of the main aims of the opening is to mobilize the pieces on useful squares where they will have impact on the game. To this end, knights are usually developed to f3, c3, f6, and c6, and both players' king and queen pawns are moved so the bishops can be developed. Rapid mobilization is the key. The queen, and to a lesser extent the rooks, are not usually played to a central position until later in the game, when many minor pieces and pawns are no longer present.
- Control of the center: At the start of the game, it is not clear on which part of the board the pieces will be needed. Controlling the central squares, however, allows pieces to be moved to any part of the board relatively easily, and can also have a cramping effect on the opponent. The classical view is that central control is best effected by placing pawns there, ideally establishing pawns on d4 and e4. However, the hypermodern school showed that it was not always necessary or even desirable to occupy the center in this way, and that too broad a pawn front could be attacked and destroyed, leaving its architect vulnerable; an impressive-looking pawn center is worth little unless it can be maintained. The hypermoderns instead advocated controlling the center from a distance with pieces, breaking down one's opponent's center, and only taking over the center oneself later in the game. This leads to openings such as Alekhine's Defense – in a line like 1.e4 Nf6 2.e5 Nd5 3.d4 d6 4.c4 Nb6 5.f4 White has a formidable pawn center for the moment, but Black hopes to undermine it later in the game, leaving White's position exposed.
- King safety: The king is somewhat exposed in the middle of the board. Measures must be taken to reduce his vulnerability. It is therefore common for both players either to castle in the opening or to otherwise bring the king to the side of the board via artificial castling.
- Most openings strive to avoid the creation of pawn weaknesses such as isolated, doubled and backward pawns, pawn islands, etc. Some openings sacrifice endgame considerations for a quick attack on the opponent's position. Some unbalanced openings for Black, in particular, make use of this idea, such as the Dutch and the Sicilian. Other openings, such as the Alekhine and the Benoni, invite the opponent to overextend and form pawn weaknesses. Specific openings accept pawn weaknesses in exchange for compensation in the form of dynamic play.
- As the players mobilize their pieces, they both seek to ensure that they are working harmoniously towards the control of key squares.
- Transposition is one common way of doing this.
Top-level objectives
At higher levels of competition, for many years the main objectives of opening play were to obtain a better position when playing as White and to equalize when playing as Black. The idea behind this is that playing first gives White a slight initial advantage; for example, White will be the first to attack if the game opens symmetrically.Since about the 1950s another objective has gradually become more dominant. According to IM Jeremy Silman, the purpose of the opening is to create dynamic imbalances between the two sides, which will determine the character of the middlegame and the strategic plans chosen by both sides. For example, in the main line of the Winawer Variation of the French Defense, White will try to use their and advantage to mount an attack on Black's, while Black will seek simplifying exchanges and counterattack against the weakened pawns on White's ; both players accept different combinations of advantages and disadvantages. This idea was a doctrine of the Soviet school of chess.
A third objective, which is complementary to the previous ones and has been common since the 19th century, is to lure the opponent into positions with which the player is more familiar and comfortable than the opponent. This is usually done by transpositions, in which a game that apparently starts with one opening can reach a position that is normally produced by a different opening.
Opening repertoires
Most players realize after a while that they play certain types of positions better than others, and that the amount of theory they can learn is limited. Therefore, most players specialize in certain openings where they know the theory and that lead to positions they favor. The set of openings a player has specialized in is called an opening repertoire. The main elements a player needs to consider in a repertoire are:- As White, whether to open with 1.e4, 1.d4, 1.c4, or 1.Nf3
- As Black, a defense against any of these openings
The main openings in a repertoire are usually reasonably sound; that is, they should lead to playable positions even against optimal counterplay. Unsound gambits are sometimes used as surprise weapons, but are unreliable for a stable repertoire. Repertoires often change as a player develops, and a player's advancement may be stifled if the opening repertoire does not evolve. Some openings that are effective against amateur players are less effective at the master level. For example, Black obtains active play in return for a pawn in the Benko Gambit; amateur players may have trouble defending against Black's activity, while masters are more skilled at defending and making use of the extra pawn. Some openings played between grandmasters are so complex and theoretical that amateur players will have trouble understanding them. An example is the Perenyi Attack of the Sicilian Defense, which yields an immensely complicated and tactical position which even strong players have difficulty handling, and which is beyond the comprehension of most amateurs.
Opening nomenclature
Major changes in the rules of chess in the late fifteenth century increased the speed of the game, consequently emphasizing the importance of opening study. Thus, early chess books, such as the 1497 text of Luis Ramirez de Lucena, present opening analysis, as do Pedro Damiano and Ruy López de Segura. Ruy López's disagreement with Damiano regarding the merits of 2...Nc6 led to 3.Bb5 being named for him as the Ruy Lopez or Spanish Opening. Opening theory was studied more scientifically from the 1840s on, and many opening variations were discovered and named in this period and later.Opening nomenclature developed haphazardly, and most names are historical accidents not based on systematic principles. In the early 1930s, the nascent FIDE embarked on a project to standardize opening nomenclature, culminating in the publication of a short booklet in 1933, but this had little impact.
The oldest openings tend to be named for geographic places and people. Many openings are named after nationalities of players who advocated them, for example Indian, English, Spanish, French, Dutch, Scotch, Russian, Italian, Scandinavian and Sicilian, or places where important games featuring the opening were played such as Vienna, Berlin, and Wilkes-Barre. The Catalan System is named after the Catalonia region.
Chess players' names are the most common sources of opening names.
The name given to an opening is not always that of the first player to adopt it; often an opening is named for the player who was the first to popularize it or to publish analysis of it. Eponymic openings include the Ruy Lopez, Alekhine's Defense, Morphy Defense, and the Réti Opening. Some opening names honor two people, such as the Caro–Kann and the Smith–Morra.
A few opening names are purely descriptive, such as Giuoco Piano, Two Knights Defense, Four Knights Game and Bishop's Opening.
Some openings have been given fanciful names, often names of animals. This practice became more common in the 20th century. By then, most of the more common and traditional sequences of opening moves had already been named, so these tend to be unusual or recently developed openings like the Orangutan, Hippopotamus, Elephant, Hedgehog, and, most recently, the Cow. A few are given humorous names, such as the Monkey's Bum and the Toilet Variation.
Opening names usually include characterizing terms like "opening", "variation", "defense", "gambit", or "attack"; however, the terminology is inconsistent and imprecise, and is not a useful basis for classification. Broadly, these terms are used as follows:
- Game: Used for some of the oldest named openings, such as the Scotch Game, Vienna Game, and Four Knights Game. In the 19th century it was used for other common openings such as the Sicilian Defense and French Defense.
- Opening: This usually refers to an opening played by White, such as the English Opening or Bird's Opening.
- Defense: Refers to an opening chosen by Black, such as Two Knights Defense or Caro-Kann Defense. Some openings described as "defenses", such as the King's Indian Defense and Sicilian Defense, can in fact be quite aggressive.
- Gambit: An opening that involves the sacrifice of, usually one or more pawns. Most openings described as "Gambits" are played by White, but a few are played by Black. The terms "Accepted" or "Declined" may be appended to the name, depending on whether the opponent takes the offered material, as in the Queen's Gambit Accepted and Queen's Gambit Declined. In the case of the Queen's Gambit, the sacrifice of material is only temporary as there is no good way for Black to keep the pawn.
- Countergambit: A gambit played by Black, often in response to another gambit. Examples of this include the Albin Countergambit in response to the Queen's Gambit, the Falkbeer Countergambit in response to the King's Gambit, and the Greco Counter Gambit in response to the King's Knight Opening.
- Variation: Used to describe a branch of another named opening, for example the Najdorf Variation, a line of the Sicilian Defense.
- System: A method of development that can be used against many different setups by the opponent. Examples include London System, Colle System, Réti System, Barcza System, and Hedgehog System.
- Attack: Usually used to describe an aggressive or provocative variation such as the Albin–Chatard Attack, the Fried Liver Attack in the Two Knights Defense, and the Grob Attack. The King's Indian Attack is an exception, describing a King's Indian Defense with.
- Reversed, inverted: A Black opening played by White, or more rarely a White opening played by Black. Examples include the Sicilian Reversed and the Inverted Hungarian. The Reti, King's Indian Attack, Sicilian Reversed, and other "Black played by White with an extra tempo" often start with 1.Nf3 or 1.c4.
- Anti-: Prefix for openings designed to avoid a specific line, for example the Anti-Marshall and the Anti-Meran Gambit.