The ''Encyclopaedia of Chess Openings'' () is a reference work describing the state of opening theory in

chess Chess is a board game for two players, called White and Black, each controlling an army of chess pieces in their color, with the objective to checkmate the opponent's king. It is sometimes called international chess or Western chess to disti ...

, originally published in five volumes from 1974 to 1979 by the

Serbia Serbia (, ; Serbian language, Serbian: , , ), officially the Republic of Serbia (Serbian language, Serbian: , , ), is a landlocked country in Southeast Europe, Southeastern and Central Europe, situated at the crossroads of the Pannonian Bas ...

n company Šahovski Informator (

Chess Informant Chess Informant (Šahovski Informator) is a publishing company from Belgrade (Serbia, former Yugoslavia) that periodically (since 2012, four volumes per year) produces a book entitled ''Chess Informant'', as well as the ''Encyclopaedia of Chess O ...

). It is currently undergoing its fifth edition. ''ECO'' may also refer to the opening classification system used by the encyclopedia.

Overview

Both ''ECO'' and ''

'' are published by the

Belgrade Belgrade ( , ;, ; Names of European cities in different languages: B, names in other languages) is the Capital city, capital and List of cities in Serbia, largest city in Serbia. It is located at the confluence of the Sava and Danube rivers a ...

-based company Šahovski Informator. The moves are taken from thousands of master games and from published analysis in ''Informant'' and compiled by the editors, most of whom are grandmasters, who select the lines which they consider most relevant or critical. The chief editor since the first edition has been

Aleksandar Matanović Aleksandar Matanović (born May 23, 1930) is a Serbian chess grandmaster. Following the death of Yuri Averbakh at the age of 100 on May 7, 2022, Matanović became the oldest living grandmaster. Chess career Awarded the GM title in 1955, Matanov ...

. The openings are provided in an ''ECO'' table that concisely presents the opening lines considered most critical by the editors. ''ECO'' covers the openings in more detail than rival single volume publications such as ''

Modern Chess Openings ''Modern Chess Openings'' (usually called ) is a reference book on chess openings, first published in 1911 by the British players Richard Clewin Griffith (1872–1955) and John Herbert White (1880–1920). The fifteenth edition was published in ...

'' and ''

Nunn's Chess Openings John Denis Martin Nunn (born 25 April 1955) is an English chess grandmaster, a three-time world champion in chess problem solving, a chess writer and publisher, and a mathematician. He is one of England's strongest chess players and was forme ...

'', but in less detail than specialized opening books. The books are intended for an international audience and contain only a small amount of text, which is in several languages. The bulk of the content consists of diagrams of positions and chess moves, annotated with

symbols A symbol is a mark, sign, or word that indicates, signifies, or is understood as representing an idea, object, or relationship. Symbols allow people to go beyond what is known or seen by creating linkages between otherwise very different conc ...

, many of them developed by Chess Informant. Chess Informant pioneered the use of Figurine Algebraic Notation to avoid the use of initials for the names of the pieces, which vary between languages. Instead of the traditional names for the openings, ''ECO'' has developed a coding system that has also been adopted by other chess publications. There are five main categories, "A" to "E", corresponding to the five volumes of the earlier editions, each of which is further subdivided into 100 subcategories, for a total of 500 codes. The term "''ECO''" is often used as a shorthand for this coding system. ''ECO'' code is a registered trademark of Chess Informant.

Openings covered

Volume A:
Flank opening A flank opening is a chess opening played by White and typified by play on one or both flanks (the portion of the chess board outside the central d and e files). White often plays in hypermodern style, attacking the center from the flanks with ...
s

English Opening The English Opening is a chess opening that begins with the move: :1. c4 A flank opening, it is the fourth most popular and, according to various databases, one of the four most successful of White's twenty possible first moves. White begins th ...

Benoni Defence The Benoni Defense is a chess opening characterized by an early reply of ...c5 against White's opening move 1.d4. Most commonly, it is reached by the sequence: :1. d4 Nf6 :2. c4 c5 :3. d5 Black can then sacrifice a pawn with 3...b5 (the Benk ...

Dutch Defence The Dutch Defence is a chess opening characterised by the moves: :1. d4 f5 Black's 1...f5 stakes a claim to the e4-square and envisions an attack in the middlegame on White's ; however, it also weakens Black's kingside to an extent (especia ...

Réti Opening The Réti Opening is a hypermodern chess opening whose "traditional" or "classic method" begins with the moves: :1. Nf3 d5 :2. c4 White attacks Black's pawn from the , which may occasion 2...dxc4. White may couple this plan with a kingside ...

Benko Gambit The Benko Gambit (or Volga Gambit) is a chess opening characterised by the move 3...b5 in the Benoni Defence arising after: :1. d4 Nf6 :2. c4 c5 :3. d5 b5 Black sacrifices a pawn for enduring pressure. White can accept or decline the gamb ...

Old Indian Defence The Old Indian Defense is a chess opening defined by the moves: :1. d4 Nf6 :2. c4 d6 This opening is distinguished from the King's Indian Defense in that Black develops their on e7 rather than by fianchetto on g7. Mikhail Chigorin pioneer ...

Bird's Opening Bird's Opening (or the Dutch Attack) is a chess opening characterised by the move: :1. f4 Bird's is a standard flank opening. White's strategic ideas involve control of the e5-square, offering good attacking chances at the expense of slightly ...

* Anti-

Indian Indian or Indians may refer to: Peoples South Asia * Indian people, people of Indian nationality, or people who have an Indian ancestor ** Non-resident Indian, a citizen of India who has temporarily emigrated to another country * South Asia ...

systems (

Trompowsky Attack The Trompowsky Attack (or Trompowsky Opening, also known as the Opočenský Opening, the Ruth Opening, and the Zot) is a chess opening that begins with the moves: :1. d4 Nf6 :2. Bg5 White prepares to exchange the bishop for Black's knight, i ...

Torre Attack The Torre Attack is a chess opening characterized by the moves: :1. d4 Nf6 :2. Nf3 e6 :3. Bg5 ('' ECO'' code A46) or the Tartakower Variation in the Queen's Pawn Game (''ECO'' code D03): :2... d5 :3. Bg5 or the Torre Attack in the East ...

Richter–Veresov Attack The Richter–Veresov Attack (or Veresov Opening) is a chess opening that begins with the moves: :1. d4 d5 :2. Nc3 Nf6 :3. Bg5 It is also often reached by transposition, for example 1.d4 Nf6 2.Nc3 d5 3.Bg5 (the most common move order), 1. ...

) * Irregular openings, etc.

Volume B:
Semi-Open Game A Semi-Open Game is a chess opening in which White plays 1.e4 and Black breaks symmetry immediately by replying with a move other than 1...e5. The Semi-Open Games are also called Single King Pawn, Asymmetrical King Pawn, or Half-Open Games (or Ope ...
s other than the French Defence

Sicilian Defence The Sicilian Defence is a chess opening that begins with the following moves: :1. b:Chess Opening Theory/1. e4, e4 b:Chess Opening Theory/1. e4/1...c5, c5 The Sicilian is the most popular and best-scoring response to White's first move 1.e4. Ope ...

* Caro-Kann Defence *

Pirc Defence The Pirc Defence (pronounced ) is a chess opening characterised by the response of Black to 1.e4 with 1...d6 and 2...Nf6, followed by ...g6 and ...Bg7, while allowing White to establish a with pawns on d4 and e4. It is named after the Slovenian ...

Alekhine's Defence The Alekhine's Defence is a chess opening that begins with the moves: :1. e4 Nf6 Black tempts White's pawns forward to form a broad , with plans to undermine and attack the white structure later in the spirit of hypermodern defence. White's i ...

Modern Defence The Modern Defense (also known as the Robatsch Defence after Karl Robatsch) is a hypermodern chess opening in which Black allows White to occupy the with pawns on d4 and e4, then proceeds to attack and undermine this "ideal" center without att ...

Scandinavian Defence The Scandinavian Defense (or Center Counter Defense, or Center Counter Game) is a chess opening characterized by the moves: :1. e4 d5 This opening is classified under code B01 in the ''Encyclopaedia of Chess Openings'' (). The Scandinavian ...

, etc.

Volume C:
Open Game An Open Game (or Double King's Pawn Opening) is a chess opening that begins with the following moves: :1. b:Chess Opening Theory/1. e4, e4 b:Chess Opening Theory/1. e4/1...e5, e5 White has moved the king's pawn two squares and Black has replied in ...
s and the French Defence

Ruy Lopez The Ruy Lopez (; ), also called the Spanish Opening or Spanish Game, is a chess opening characterised by the moves: :1. e4 e5 :2. Nf3 Nc6 :3. Bb5 The Ruy Lopez is named after 16th-century Spanish priest Ruy López de Segura. It is one o ...

French Defence The French Defence is a chess opening characterised by the moves: :1. e4 e6 This is most commonly followed by 2.d4 d5, with Black intending ...c5 soon after, attacking White's and gaining on the . The French has a reputation for solidity ...

Petrov's Defence Petrov's Defence or the Petrov Defence (also called Petroff Defence, Petrov's Game, Russian Defence, or Russian Game – russian: Русская партия) is a chess opening characterised by the following moves: :1. e4 e5 :2. Nf3 Nf6 Tho ...

Vienna Game The Vienna Game is an opening in chess that begins with the moves: :1. e4 e5 :2. Nc3 White's second move is less common than 2.Nf3, and is also more recent. The original idea behind the Vienna Game was to play a delayed King's Gambit with f ...

Centre Game The Center Game is a chess opening that begins with the moves: :1. e4 e5 :2. d4 exd4 The game usually continues 3.Qxd4 Nc6, with a gain of tempo for Black due to the attack on the white queen. (Note that 3.c3 is considered a separate open ...

King's Gambit The King's Gambit is a chess opening that begins with the moves: :1. e4 e5 :2. f4 White offers a pawn to divert the black e-pawn. If Black accepts the gambit, White has two main plans. The first is to play d4 and Bxf4, regaining the gambit p ...

Philidor Defence The Philidor Defence (or Philidor's Defence) is a chess opening characterised by the moves: :1. e4 e5 :2. Nf3 d6 The opening is named after the famous 18th-century player François-André Danican Philidor, who advocated it as an alternative ...

Italian Italian(s) may refer to: * Anything of, from, or related to the people of Italy over the centuries ** Italians, an ethnic group or simply a citizen of the Italian Republic or Italian Kingdom ** Italian language, a Romance language *** Regional Ita ...

(

Giuoco Piano The Giuoco Piano (Italian: "Quiet Game"; ), also called the Italian Opening, is a chess opening beginning with the moves: :1. e4 e5 :2. Nf3 Nc6 :3. Bc4 Bc5 "White aims to develop quickly – but so does Black. White can construct a pawn cen ...

Evans Gambit The Evans Gambit is a chess opening characterised by the moves: :1. e4 e5 :2. Nf3 Nc6 :3. Bc4 Bc5 :4. b4 The Evans Gambit is an aggressive line of the Giuoco Piano. White offers a pawn to divert the black bishop on c5. If Black accepts, ...

Hungarian Defence The Hungarian Defense is a chess opening that begins with the moves: :1. e4 e5 :2. Nf3 Nc6 :3. Bc4 Be7 The Hungarian Defense is a line in the Italian Game typically chosen as a response to the aggressive 3.Bc4. With the move 3...Be7, Black ...

, and Two Knights) *

Scotch Game The Scotch Game, or Scotch Opening, is a chess opening that begins with the moves: :1. e4 e5 :2. Nf3 Nc6 :3. d4 Ercole del Rio, in his 1750 treatise ''Sopra il giuoco degli Scacchi, Osservazioni pratiche d’anonimo Autore Modenese'' ("On t ...

Four Knights Game The Four Knights Game is a chess opening that begins with the moves: :1. e4 e5 :2. Nf3 Nc6 :3. Nc3 Nf6 This is the most common sequence, but the knights may in any order to reach the same position. The opening is fairly popular with begin ...

, etc. *

King's Pawn Opening The King's Pawn Game is any chess opening starting with the move: :1. e4 It is the most popular opening move in chess, followed by the Queen's Pawn Game. Details about the move and the game plan White opens with the most popular of the twen ...

, etc. (covers unusual/rare 1. e4 openings such as the

Elephant Gambit The Elephant Gambit (also called the Queen's Pawn Countergambit or Englund Counterattack) is a rarely played chess opening beginning with the moves: :1. e4 e5 :2. Nf3 d5 Although the Elephant Gambit is considered unsound, it has been used fr ...

and

Ponziani Opening The Ponziani Opening is a chess opening that begins with the moves: :1. e4 e5 :2. Nf3 Nc6 :3. c3 It is one of the oldest chess openings, having been discussed in the literature by 1497. It was advocated by Howard Staunton, generally conside ...

Volume D:
Closed Game A Closed Game (or Double Queen's Pawn Opening) is a chess opening that begins with the moves: :1. d4 d5 The move 1.d4 offers the same benefits to and as does 1.e4, but unlike with the king's pawn openings where the e4-pawn is undefended after ...
s and
Semi-Closed Game A Semi-Closed Game (or Semi-Closed Opening) is a chess opening in which White plays 1.d4 but Black does not make the symmetrical reply 1...d5. (The openings starting 1.d4 d5 are the Closed Games.) Important openings By far the most important ...
s

:(''including Grünfeld Defence but not other Indian Defenses'') *

Queen's Gambit The Queen's Gambit is the chess opening that starts with the moves: :1. d4 d5 :2. c4 It is one of the oldest openings and is still commonly played today. It is traditionally described as a ''gambit'' because White appears to sacrifice the c ...

Accepted ''Accepted'' is a 2006 American comedy film directed by Steve Pink (in his directorial debut) and written by Adam Cooper, Bill Collage and Mark Perez. The plot follows a group of high school graduates who create their own fake college after bein ...

** Declined (

Slav Slavs are the largest European ethnolinguistic group. They speak the various Slavic languages, belonging to the larger Balto-Slavic branch of the Indo-European languages. Slavs are geographically distributed throughout northern Eurasia, main ...

Orthodox Orthodox, Orthodoxy, or Orthodoxism may refer to: Religion * Orthodoxy, adherence to accepted norms, more specifically adherence to creeds, especially within Christianity and Judaism, but also less commonly in non-Abrahamic religions like Neo-pa ...

, Tarrasch, Tartakower,

Albin Countergambit The Albin Countergambit is a chess opening that begins with the moves: :1. d4 d5 :2. c4 e5 and the usual continuation is: :3. dxe5 d4 The opening is an uncommon defense to the Queen's Gambit. In exchange for the gambit pawn, Black has a ...

, etc.) *

Grünfeld Defence The Grünfeld Defence is a chess opening characterised by the moves: :1. d4 Nf6 :2. c4 g6 :3. Nc3 d5 Black offers White the possibility of 4.cxd5, which may be followed by 4...Nxd5 and 5.e4, giving White an imposing central pawn duo. If Whi ...

Queen's Pawn Game Queen's Pawn Game broadly refers to any chess opening starting with the move 1.d4, which is the second most popular opening move after 1.e4 ( King's Pawn Game). Terminology The term "Queen's Pawn Game" is usually used to describe openings begi ...

, etc.

Volume E: Indian Defences

:(''other than Grünfeld Defence and Old Indian Defence'') *

Nimzo-Indian Defence The Nimzo-Indian Defence is a chess opening characterised by the moves: :1. d4 Nf6 :2. c4 e6 :3. Nc3 Bb4 Other move orders, such as 1.c4 e6 2.Nc3 Nf6 3.d4 Bb4, are also feasible. In the ''Encyclopaedia of Chess Openings'', the Nimzo-Indian ...

Queen's Indian Defence The Queen's Indian Defense (QID) is a chess opening defined by the moves: :1. d4 Nf6 :2. c4 e6 :3. Nf3 b6 The opening is a solid defense to the Queen's Pawn Game. 3...b6 increases Black's control over the central light squares e4 and d5 by ...

King's Indian Defence The King's Indian Defence is a common chess opening. It is defined by the following moves: :1. d4 Nf6 :2. c4 g6 Black intends to follow up with 3...Bg7 and 4...d6 (the Grünfeld Defence arises when Black plays 3...d5 instead, and is cons ...

Catalan Opening The Catalan Opening is a chess opening where White plays d4 and c4 and fianchettoes the white bishop on g2. A common opening sequence is 1.d4 Nf6 2.c4 e6 3.g3, although various other openings can transpose into the Catalan. The ''Encyclopaedia of ...

* Bogo-Indian Defence, etc.

Main ''ECO'' codes

A

* White first moves other than 1.e4, 1.d4 (A00–A39) * 1.d4 without 1...d5, 1...Nf6 or 1...f5: Atypical replies to 1.d4 (A40–A44) * 1.d4 Nf6 without 2.c4: Atypical replies to 1...Nf6 (A45–A49) * 1.d4 Nf6 2.c4 without 2...e6, 2...g6: Atypical Indian systems (A50–A79) * 1.d4 f5:

(A80–A99)

B

* 1.e4 without 1...c6, 1...c5, 1...e6, 1...e5 (B00–B09) * 1.e4 c6:

Caro–Kann Defence The Caro–Kann Defence is a chess opening characterised by the moves: :1. b:Chess Opening Theory/1. e4, e4 b:Chess Opening Theory/1. e4/1...c6, c6 The Caro–Kann is a common defence against the King's Pawn Opening. It is classified as a Semi-Op ...

(B10–B19) * 1.e4 c5:

(B20–B99)

C

* 1.e4 e6:

(C00–C19) * 1.e4 e5: Double King Pawn games (C20–C99)

D

* 1.d4 d5: Double Queen Pawn games (D00–D69) * 1.d4 Nf6 2.c4 g6 with 3...d5:

(D70–D99)

E

* 1.d4 Nf6 2.c4 e6: Indian systems with ...e6 (E00–E59) * 1.d4 Nf6 2.c4 g6 without 3...d5: Indian systems with ...g6 (except Grünfeld) (E60–E99)

First edition

The first edition was published in the following years: * Volume A: 1979 * Volume B: 1975 * Volume C: 1974 * Volume D: 1976 * Volume E: 1978

Second edition

The second edition was published in the following years: * Volume A: 1996 * Volume B: 1984 * Volume C: 1981 * Volume D: 1987 * Volume E: 1991

Third edition

The third edition was published in the following years: * Volume A: 1999 * Volume B: 1997 * Volume C: 1997 * Volume D: 1998 * Volume E: 1998

Fourth edition

The fourth edition was published in the following years: * Volume A: 2001 * Volume B: 2002 * Volume C: 2000 * Volume D: 2004 * Volume E: 2008

Fifth edition

The fifth edition was published in the following years: * Volume C: 2006 * Volume B part 1 CO codes: B00–B49 2020 * Volume B part 2 CO codes: B50-B99 2021

References

* * *

External links

* Publisher's site * ''ECO'' codes with names {{Chess, state=collapsed *Encyclopedia of Chess Openings Chess books Chess in Serbia 20th-century encyclopedias