Chess openings

The first moves of a chess game are the opening moves, collectively referred to as the opening. Recognized sequences of opening moves are referred to as openings or defenses, and have been given names such as the Ruy Lopez, Sicilian Defense, and Queen's Gambit Declined. There are dozens of different openings, which vary widely in character from quiet positional play (e.g. the Réti Opening and some lines of the Queen's Gambit Declined) to wild tactical play (e.g. the Latvian Gambit and Two Knights Defense, particularly the Wilkes-Barre Variation).

A sequence of opening moves that is considered standard or follows that given in a reference work (such as the Encyclopedia of Chess Openings) is referred to as "the book moves" or simply "book". These reference works often present these move sequences in simple algebraic notation, opening trees, or theory tables. A new move in the opening is referred to as a "novelty" or "theoretical novelty". When a game begins to deviate from known opening theory, the players are said to be "out of book". In some opening lines, the moves considered best for both sides have been worked out to 30-35 moves or more. Professional chessplayers spend years studying openings, and continue doing so throughout their careers, as opening theory constantly evolves.

Aims of the opening

Although a wide variety of moves are played in the opening, the aims behind them are, broadly speaking, the same. First and foremost, the aim is to avoid being checkmated and avoid losing material, as in other phases of the game. However, assuming neither player makes a blunder in the opening, the main aims include:

1. Development: One of the main aims of the opening is to place (develop) 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 (or sometimes e2, d2, e7 or d7), and both player's e- and d-pawns are moved so the bishops can be developed (alternatively, the bishops may be fianchettoed with a manoeuvre such as g3 and Bg2). The more rapidly the pieces are developed, the better. The queen, however, is not usually played to a central position until later in the game, as it is liable to be attacked otherwise, when its value means it has to be moved, which can waste time.

2. 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. However, control of the central squares 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 (or d5 and e5 for Black). 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 centre from a distance with pieces, breaking down one's opponent center, and only taking over the center oneself later in the game. This leads to openings such as the Alekhine Defense - in a line like 1. e4 Nf6 2. e5 Nd5 3. d4 d6 4. c4 Nb6 5. f4 (the Four Pawns Attack) White has a formidable pawn center for the moment, but Black hopes to undermine it later in the game, leaving White's position exposed.

3. King safety: The king is somewhat exposed in the middle of the board. It is therefore normal for both players to either castle in the opening (simultaneously developing one of the rooks) or to otherwise bring the king to the side of the board via artificial castling.

4. Pawn weaknesses: Most openings strive to avoid the creation of pawn weaknesses such as isolated, doubled and backward pawns, pawn islands, etc. Certain 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. While other openings, such as the Alekhine and the Benoni invite the opponent to overextend and form pawn weaknesses. Certain openings accept pawn weaknesses in exchange for compensation in the form of dynamic play.

Apart from these ideas, other strategic plans used in the middlegame may also be carried out in the opening. These include preparing pawn breaks to create counterplay, creating weaknesses in the opponent's pawn structure, seizing control of key squares, making favourable exchanges of minor pieces (e.g. gaining the bishop pair), or gaining a space advantage, whether in the centre or on the flanks.

In more general terms, many writers (for example, Reuben Fine in The Ideas Behind the Chess Openings) have commented that it is White's task in the opening to preserve and increase the advantage conferred by moving first, while Black's task is to equalise the game. Many openings, however, give Black a chance to play aggressively for advantage from the very start.

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 Winawer Variation of the French, White will try to use his bishop pair and space advantage to mount an attack on Black's kingside, while Black will seek simplifying exchanges (in particular, trading off one of White's bishops to blunt this advantage) and counterattack against the weakened pawns on White's queenside.

Opening nomenclature

Early in the history of chess the lack of an adequate or widely used system of chess notation made it very cumbersome to describe the opening moves of a game. It was natural to assign names to sequences of opening moves to make them easier to discuss. Opening theory began being studied more scientifically from the 1840s on, and many opening variations were discovered and named in this period and later. Unfortunately opening nomenclature developed haphazardly, and most names are more historical accidents than based on any systematic principles.

The oldest openings tend to be named for geographic places and people. Many openings are named after nationalities, for example English, Spanish, French, Dutch, Scotch, Russian, Italian, Scandinavian, and Sicilian. Cities are also used, such as Vienna, Berlin, and Wilkes-Barre. The Catalan System is named after the Catalonia region of Spain.

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 Defense, Morphy Defense, and the Réti System. Some opening names honor two people, such as with the Caro-Kann.

A few opening names are descriptive, such as Giuoco Piano (Italian: "quiet game"). More prosaic descriptions include Two Knights and Four Knights. Descriptive names are less common than openings named for places and people.

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, and Hedgehog.

Many terms are used for the opening as well. In addition to Opening, common terms include Game, Defense, Gambit, and Variation; less common terms are System, Attack, Counterattack, Countergambit, Reversed, and Inverted. To make matters more confusing, these terms are used very inconsistently. Consider some of the openings named for nationalities: Scotch Game, English Opening, French Defense, and Russian Game — the Scotch Game and the English Opening are both White openings, the French is indeed a defense but so is the Russian Game. Although these don't have precise definitions, here are some general observations about how they are used.

Game
Used only for some of the oldest openings, for example Scotch Game, Vienna Game, and Four Knights Game.

Opening
Along with Variation, this is the most common term.

Variation
Usually used to describe a line within a more general opening, for example the Exchange Variation of the Queen's Gambit Declined.

Defense
Always refers to an opening chosen by Black, such as Two Knights Defense or Kings Indian Defense, unless, of course, it has 'reversed' in front of it, which makes it an opening for white.

Gambit
An opening that involves the sacrifice of material, usually one or more pawns. Gambits can be played by White (e.g., King's Gambit) or Black (e.g., Latvian Gambit). The full name often includes Accepted or Declined depending on whether the opponent took the offered material, as in the Queen's Gambit Accepted and Queen's Gambit Declined. In some cases, the sacrifice of material is only temporary. For example, after 1.d4 d5 2.c4 dxc4 (the Queen's Gambit Accepted), White can regain the pawn immediately by 3.Qa4+ if he wishes.

Countergambit
A gambit offered in response to an opponent's gambit; or, any gambit played by Black. Examples of this include the Falkbeer Countergambit to the King's Gambit and the Greco Counter Gambit (an old-fashioned name for the Latvian Gambit).

System
A method of development that can be used against many different setups by the opponent. Examples include Réti System, Barcza System, and Hedgehog System.

Attack
Sometimes used to describe an aggressive or provocative variation such as the Albin-Chatard Attack (or Chatard-Alekhine Attack), the Fried Liver Attack in the Two Knights Defense, and the Grob Attack. In other cases it refers to a defensive system by Black when adopted by White, as in King's Indian Attack. In still other cases the name seems to be used ironically, as with the fairly inoffensive Durkin's Attack (also called the Durkin Opening).

Reversed, Inverted
A Black opening played by White, or more rarely a White opening played by Black. Examples include Sicilian Reversed (from the English Opening), and the Inverted Hungarian.

A small minority of openings are prefixed with "Anti-". These are openings intended to avoid a particular line otherwise available to one's opponent, for example the Anti-Marshall (against the Marshall (Counter) Attack in the Ruy Lopez) and the Anti-Meran Gambit (against the Meran Variation of the Semi-Slav Defense).

Classification of chess openings

Various classification schemes for chess openings are in use. The ECO scheme is given at list of chess openings.

The beginning chess position offers White 20 possible first moves. Of these, 1.e4, 1.d4, 1.Nf3, and 1.c4 are by far the most popular as these moves do the most to promote rapid development and control of the center. A few other opening moves are considered reasonable but less consistent with opening principles than the four most popular moves. The Dunst Opening, 1.Nc3, develops a knight to a good square, but is somewhat inflexible because it blocks White's c-pawn; also, after 1...d5 the knight is liable to be kicked to an inferior square by ...d4. (Note that after 1.Nf3 the analogous 1...e5? just loses a pawn.) Bird's Opening, 1.f4, addresses center control but not development and weakens the king position slightly. The Sokolsky Opening 1.b4 and the King's and Queen's fianchettos 1.b3 and 1.g3 aid development a bit, but they only address center control peripherally and are slower than the more popular openings. The 11 remaining possibilities are rarely played at the top levels of chess. Of these, the best are merely slow such as 1.c3, 1.d3, and 1.e3. Worse possibilities either ignore the center and development like 1.a3, weaken White's position (for instance, 1.f3 and 1.g4), or place the knights on poor squares (1.Na3 and 1.Nh3).

Black has 20 possible responses to White's opening move. Many of these are mirror images of the most popular first moves for White, but with a tempo less. Defenses beginning with 1...c6 and 1...e6, often followed by the center thrust 2...d5, are also popular. Defenses with an early ...d6 coupled with a king-side fianchetto are also commonly played.

One reasonable way to group the openings is

* Double King Pawn or Open Games (1.e4 e5)
* Single King Pawn or Semi-Open Games (1.e4 other)
* Double Queen Pawn or Closed Games (1.d4 d5)
* Single Queen Pawn or Semi-Closed Games(1.d4 other)
* Flank Openings (including 1.c4, 1.Nf3, 1.f4, and others)
* Unusual first moves for White

Open games (1.e4 e5)

White starts by playing 1.e4 (moving his King's pawn 2 spaces). This is the most popular opening move and it has many strengths — it immediately works on controlling the center, and it frees two pieces (the queen and a bishop). The oldest openings in chess follow 1.e4 and many lie along the Épine Dorsale. Bobby Fischer rated 1.e4 as "best by test". On the downside, 1.e4 places a pawn on an undefended square and weakens d4 and f4; the Hungarian master Gyula Breyer melodramatically declared that "After 1.e4 White's game is in its last throes". If Black mirrors White's move and replies with 1...e5, the result is an open game.

The most popular second move for White is 2.Nf3 attacking Black's king pawn, preparing for a kingside castle, and anticipating the advance of the queen pawn to d4. Black's most common reply is 2...Nc6, which usually leads to the Ruy Lopez, Giuoco Piano, Two Knights Defense, or Scotch Game. If Black instead maintains symmetry and counterattacks White's center with 2...Nf6 then the Petrov's Defense results.

The most popular alternatives to 2.Nf3 are 2.Nc3 (the Vienna Game), 2.Bc4 (the Bishop's Opening) and 2.f4 (the King's Gambit). All of these three openings have some similarities with each other, in particular the Bishop's Opening frequently transposes to variations of the Vienna Game. The King's Gambit was extremely popular in the 1800s. White sacrifices a pawn for quick development and to pull a black pawn out of the center. The Vienna Game also frequently features attacks on the Black center by means of a f2-f4 pawn advance.

In the Center Game, 2.d4, White immediately opens the center but if the pawn is to be recovered after 2...exd4, White must contend with a slightly premature queen development after 3.Qxd4. An alternative is to sacrifice one or two pawns, for example in the Danish Gambit. The early queen developments of the Parham Attack and the Napoleon Opening look amateurish. Indeed they are generally only played by novices, but the Parham Attack has been played in a few grandmaster tournament games. The Portuguese Opening, Alapin's Opening, Konstantinopolsky Opening, and Inverted Hungarian Opening are rare, offbeat tries for White.

Of the defenses in this section, only the Damiano Defense is truly bad, although the Elephant Gambit and the Latvian Gambit are very risky for Black. The Philidor Defense is not popular in modern chess because it allows White an easy space advantage while Black remains solid but cramped and passive.

* 1.e4 e5 Double King's Pawn Opening or Open Game
* 1.e4 e5 2.Nf3 Nc6 3.Bb5 Ruy Lopez
* 1.e4 e5 2.Nf3 Nc6 3.c3 Ponziani Opening
* 1.e4 e5 2.Nf3 Nc6 3.d4 Scotch Game
* 1.e4 e5 2.Nf3 Nc6 3.Bc4 Italian Game
* 1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 Giuoco Piano
* 1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.b4 Evans Gambit
* 1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 Two Knights Defense
* 1.e4 e5 2.Nf3 Nc6 3.Bc4 Be7 Hungarian Defense
* 1.e4 e5 2.Nf3 Nc6 3.Nc3 Nf6 Four Knights Game
* 1.e4 e5 2.Nf3 Nc6 3.Nc3 something besides 3...Nf6 Three Knights Game
* 1.e4 e5 2.Nf3 Nc6 3.g3 Konstantinopolsky Opening
* 1.e4 e5 2.Nf3 Nf6 Petrov's Defense
* 1.e4 e5 2.Nf3 d6 Philidor Defense
* 1.e4 e5 2.Nf3 f5 Latvian Gambit
* 1.e4 e5 2.Nf3 d5 Elephant Gambit
* 1.e4 e5 2.Nf3 Qf6 Greco Defense
* 1.e4 e5 2.Nf3 f6 Damiano Defense
* 1.e4 e5 2.Bc4 Bishop's Opening
* 1.e4 e5 2.Nc3 Vienna Game
* 1.e4 e5 2.f4 King's Gambit
* 1.e4 e5 2.d4 exd4 3.Qxd4 Center Game
* 1.e4 e5 2.d4 exd4 3.c3 Danish Gambit
* 1.e4 e5 2.Qh5 Parham Attack
* 1.e4 e5 2.Bb5 Portuguese Opening
* 1.e4 e5 2.c3 Lopez Opening
* 1.e4 e5 2.Nf3 Nc6 3.Be2 Inverted Hungarian Opening
* 1.e4 e5 2.Ne2 Alapin's Opening
* 1.e4 e5 2.Qf3?! Napoleon Opening

Semi-open games (1.e4, Black plays something other than 1...e5)

In the semi-open games White plays 1.e4 and Black breaks symmetry immediately by replying with a move other than 1...e5. The most popular Black defense to 1.e4 is the Sicilian, but the French and the Caro-Kann are also very popular. The Pirc and the Modern are also commonly seen, while the Alekhine and the Scandinavian have made occasional appearances in World Chess Championship games. The Nimzowitsch is playable but rare, as is Owen's Defense. The Grob Defense and the St. George Defense are oddities, although Tony Miles once used St. George's Defense to defeat then World Champion Anatoly Karpov.

The Sicilian and French Defenses lead to unbalanced positions that can offer exciting play with both sides having chances to win. The Caro-Kann Defense is solid as Black intends to use his c-pawn to support his center (1.e4 c6 2.d4 d5). Alekhine's, the Pirc and the Modern are hypermodern openings in which Black tempts White to build a large center with the goal of attacking it with pieces.

* 1.e4 a6 St. George Defense
* 1.e4 b6 Owen's Defense
* 1.e4 c5 Sicilian Defense
* 1.e4 c6 Caro-Kann Defense
* 1.e4 Nc6 Nimzowitsch Defense
* 1.e4 d5 Scandinavian Defense
* 1.e4 d6 2.d4 Nf6 3.Nc3 g6 Pirc Defense
* 1.e4 e6 French Defense
* 1.e4 e6 2.d4 c5 Franco-Benoni Defense
* 1.e4 Nf6 Alekhine's Defense
* 1.e4 g5 Grob Defense
* 1.e4 g6 Modern Defense
* 1.e4 f5 Fred Defense

Closed games (1.d4 d5)

The openings classified as closed games begin 1.d4 d5. The move 1.d4 offers the same benefits to development and center control as does 1.e4, but unlike with the King Pawn openings where the e4 pawn is undefended after the first move, the d4 pawn is protected by White's queen. This slight difference has a tremendous effect on the opening. For instance, whereas the King's Gambit is rarely played today at the highest levels of chess, the Queen's Gambit remains a popular weapon at all levels of play. Also, compared with the King Pawn openings, transpositions between variations are more common and critical in the closed games.

The Richter-Veresov Attack, Colle System, Stonewall Attack, and Blackmar-Diemer Gambit are classified as Queen's Pawn Games because White plays d4 but not c4. Although the Richter-Veresov is played at the top levels of chess, it is used only occasionally. The Colle and the Stonewall are both Systems, rather than specific opening variations. White develops aiming for a particular formation without great concern over how Black chooses to defend. Both these systems are popular with club players because they are easy to learn, but are rarely used by professionals because a well prepared opponent playing Black can equalize fairly easily. The Blackmar-Diemer Gambit is an attempt by White to open lines and obtain attacking chances. Most professionals consider it too risky for serious games, but it is popular with amateurs and in blitz chess.

The most important closed openings are in the Queen's Gambit family (White plays 2.c4). The Queen's Gambit is somewhat misnamed, since White can always regain the offered pawn if desired. In the Queen's Gambit Accepted, Black plays ...dxc4, giving up the center for free development and the chance to try to give White an isolated queen pawn with a subsequent ...c5 and ...cxd5. White will get active pieces and possibilities for the attack. Black has two popular ways to decline the pawn, the Slav (2...c6) and the Queen's Gambit Declined (2...e6). Both of these moves lead to an immense forest of variations that can require a great deal of opening study to play well. Among the many possibilities in the Queen's Gambit Declined are the Orthodox Defense, Lasker's Defense, the Cambridge Springs Defense, the Tartakower Variation, and the Tarrasch and Semi-Tarrasch Defenses.

Black replies to the Queen's Gambit other than 2...dxc4, 2...c6, and 2...e6 are uncommon. The Chigorin Defense (2...Nc6) is playable but quite rare. The Symmetrical Defense (2...c5) is the most direct challenge to Queen's Gambit theory — Can Black equalize by simply copying White's moves? Most opening theoreticians believe the answer is no, and consequently the Symmetrical Defense is not popular. The Baltic Defense (2...Bf5) takes the most direct solution to solving the problem of Black's queen bishop by developing it on the second move. Although it is not trusted by most elite players, it has not been definitely refuted and some very strong grandmasters have played it. The Albin Countergambit (2...e5) is generally considered too risky for top-level tournament play, and the Marshall Defense (2...Nf6) is no longer played as it is thought to be definitely inferior for Black.

* 1.d4 d5 Double Queen's Pawn Opening or Closed Game
* 1.d4 d5 2.Nc3 Nf6 3.Bg5 Richter-Veresov Attack
* 1.d4 d5 2.c4 Queen's Gambit
* 1.d4 d5 2.c4 dxc4 Queen's Gambit Accepted (QGA)
* 1.d4 d5 2.c4 c5 Symmetrical Defense
* 1.d4 d5 2.c4 c6 Slav Defense
* 1.d4 d5 2.c4 Nc6 Chigorin Defense
* 1.d4 d5 2.c4 e5 Albin Countergambit
* 1.d4 d5 2.c4 e6 Queen's Gambit Declined (QGD)
* 1.d4 d5 2.c4 Bf5 Baltic Defense
* 1.d4 d5 2.c4 Nf6 Marshall Defense
* 1.d4 d5 2.e3 Stonewall Attack
* 1.d4 d5 2.e4 Blackmar-Diemer Gambit
* 1.d4 d5 2.Nf3 Nf6 3.e3 Colle System

Indian systems (1.d4 Nf6)

The Indian systems are asymmetrical defenses to 1.d4 that employ hypermodern chess strategy. Fianchettos are common in many of these openings. As with the closed games, transpositions are important and many of the Indian defenses can be reached by several different move orders. Although Indian defenses were championed in the 1920s by players in the hypermodern school, they were not fully accepted until Soviet players showed in the late 1940s that these systems are sound for Black. Since then, Indian defenses have been the most popular Black replies to 1.d4 because they offer an unbalanced game with chances for both sides.

The Modern Benoni Defense is a risky attempt by Black to unbalance the position and gain active piece play at the cost of allowing White a pawn wedge at d5 and a central majority. Tal popularized the defense in the 1960s by winning several brilliant games with it. Often Black adopts a slightly different move order, playing 2...e6 before 3...c5.

The Benko Gambit is now considered a sound opening for Black. Black plays to open lines on the queenside where White will be subject to considerable pressure. If White accepts the gambit, Black's compensation is positional rather than tactical, and his initiative can last even after many piece exchanges and well into the endgame. White often chooses instead either to decline the gambit pawn or return it.

Advocated by Nimzowitsch as early as 1913, the Nimzo-Indian Defense was the first of the Indian systems to gain full acceptance. It remains one of the most popular and well-respected defenses to 1.d4. Black attacks the center with pieces and is prepared to trade a bishop for a knight to weaken White's queenside with doubled pawns.

The Queen's Indian Defense is considered solid, safe, and perhaps somewhat drawish. Black often chooses the Queen's Indian when White avoids the Nimzo-Indian by playing 3.Nf3 instead of 3.Nc3. Black constructs a sound position that makes no positional concessions, although sometimes it is difficult for Black to obtain good winning chances. Karpov is a leading expert in this opening.

The King's Indian Defense is aggressive and somewhat risky, and generally indicates that Black will not be satisfied with a draw. Although it was played occasionally as early as the late 19th century, the King's Indian was considered inferior until the 1940s when it was featured in the games of Bronstein, Boleslavsky, and Reshevsky. Fischer's favored defense to 1.d4, its popularity faded in the mid-1970s. Kasparov's successes with the defense restored the King's Indi