Encyclopedia of Chess Openings (ECO)

ECO classifies chess openings using codes from A00 to E99. For your use is a comprehensive collection of modern opening theory, see in chess viewer a complete list of the chess openings along with their classifications in the ECO.

What is a “Chess Opening”?!

“When you see a good move, wait – look for a better one.” – Emanuel Lasker, 2nd World Chess Champion

Chess opening goals

The main purpose of opening play is to obtain the best 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 (Black mirrors White’s moves).
Playing the chess opening aimlessly may result in your opponent getting a huge advantage.
For most openings, the fundamental chess strategic aims are similar:

  • Develop your pieces – rapidly mobilize the pieces on useful squares where they will have impact on the game, keeping them in harmonious communication.
  • Move your king to safety – king is vulnerable due to his initial placement in the middle of the chess board, which is usually reduced by castling.
  • Control the center – 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. It is not always necessary or even desirable to occupy the center by pieces physically; 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. Instead the center can be controlled from a distance, breaking down one’s opponent center, and only taking over the center ones.
  • Prevention of pawn weakness – most chess openings strive to avoid the creation of pawn weaknesses such as isolated, doubled and backward pawns, pawn islands, etc. At the same time, some other openings sacrifice these endgame considerations for a quick attack on the opponent’s position

There is also a psychological element in choosing a chess opening to play: try to drag the opponent into types of positions with which you are more familiar and more comfortable playing than him

Chess Opening history

Changes in the chess rules in the late fifteenth century increased the speed of the game, consequently emphasizing the significance of opening study. Chess books were used to present chess opening analysis at that time. But the chess opening theory was given only in the middle of nineteenth century, when many opening variations were discovered and named in this period and later.
The oldest openings tend to be named for geographic places and people (like Sicilian Defense or Grunfeld Defense), later openings tended to be named after nationalities (like Spanish or French Openings). More prosaic descriptions include Two Knights and Four Knights. Descriptive names are less common than openings named for places and people.
Chess players? names are the most common sources of opening names, although 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.

Classification of chess openings

All the openings are classified by the Encyclopedia of Chess Openings, you can view all of them by clicking here.

The beginning chess position offers White twenty possible first moves. Black has twenty possible responses to White’s opening move.
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 simple descriptive grouping of the chess opening is:

  • Double King Pawn or Open Games (1.e4 e5)
  • Single King Pawn or Semi-Open Games (1.e4 other than e5 move)
  • Double Queen Pawn or Closed Games (1.d4 d5)
  • Single Queen Pawn or Semi-Closed Games (1.d4 other than d5 move)
  • Flank openings (including 1.c4, 1.Nf3, 1.f4, and others)
  • Unusual first moves

Open Games (1.e4 e5)

This is the most popular opening move in chess history ? and remains such today. Bobby Fischer rated 1.e4 as “best by test”. If Black mirrors White’s move and replies with 1…e5, the result is an open game.
1. e4 (and the mirror reply by black) have many visible strengths: immediately works on controlling the center, frees two pieces (the queen and a bishop). On the downside, it places a pawn on an undefended square and weakens d4 and f4 for White (and d5 and f5 for Black).
The most popular chess opening in this position is the Spanish Game (2. Kf3 Kc6 3.Bb5) and the Petrov’s Defense (2.Kf3 Kf6). In most variants these chess openings lead to positional balanced game.

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 breaking symmetry response to 1.e4 is the Sicilian (1…c5), the French (1…e6) or the Caro-Kann (1…c6) openings. In most variants these chess openings lead to unbalanced positions with sharp play for both sides

Closed games (1.d4 d5)

These moves offers the same benefits to development and center control that open games do, but unlike with the king pawns undefended after the first move, the pawns are protected by queens. This slight difference has a tremendous effect on the opening.
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 almost always regain the offered pawn, if desired. In most variants these chess openings lead to positional balanced game.

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

There are several popular asymmetric to 1.d4 replies for Black, each one of them lead to unique system and formation. The most important here to mention are the Indian systems (1.d4 Nf6) and the Dutch Defense (1.d4 f5).
In most variants these chess openings lead to sharp unbalanced game with chances for both sides.

Flank Openings

The flank openings are the group of White openings typified by play on one or both flanks. White usually attacks the center from the flanks with pieces rather than occupying it with pawns.
The most popular flank openings are English Opening (1.c4) and Reti Opening (1.Nf3, characteristically followed by fianchettoing one or both bishops, and without an early d4). In most variants these chess openings lead to positional equal game.

Unusual moves

First moves other than the king’s pawn (1.e4), queen’s pawn (1.d4), or flank openings (1.b3, 1.b4, 1.c4, 1.Nf3, 1.f4, or 1.g3) are not regarded as effective ways to exploit White’s first-move advantage and thus are rarely played. Although some of these openings are not actually bad for White, each of the twelve remaining possible first moves suffers one or more of the following defects compared to the more popular choices and cannot be recommended to play in “serious” games:

  • too passive for White (e.g. 1.d3, 1.e3, 1.c3, 1.Nc3)
  • gratuitously weakens White’s position (e.g., 1.f3, 1.g4)
  • does little to aid White’s development or control the center (e.g., 1.a3, 1.a4, 1.h3, 1.h4)
  • develops a knight to an inferior square (1.Na3 or 1.Nh3)

Fundamental Strategic Aims of Chess Openings

For most chess openings, the fundamental chess strategic aims are similar:

  • Development : To place (develop) the pieces (particularly bishops and knights) on useful squares where they will have an impact on the game.
  • Control of the center : 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.
  • King safety : Correct timing of castling can enhance this.
  • Pawn structure : Players strive to avoid the creation of pawn weaknesses such as isolated, doubled or backward pawns, and pawn islands.
  • Piece coordination: As each player mobilizes his or her pieces, each attempts to assure that they are working harmoniously towards the control of key squares.

Apart from these fundamentals of chess openings, other strategic plans or tactical sequences may be employed in the openings.