# Chess Opening Theory

Opening Position
 a b c d e f g h 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 a b c d e f g h
Position in Forsyth-Edwards Notation(FEN)

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In chess, unlike tennis, it is not possible to win by serving an ace.
—Irving Chernev, chess writer

The opening of a game of chess is a battle between two equally matched armies. There is no known method that will secure one player a decisive advantage over the other regardless of what the opponent does. If there were, chess as a professional sport would most likely cease to exist. Winning a game of chess depends on one's opponent making inaccurate moves. The question "What is an inaccurate move?" can best be answered by trial and error.

Take the opening position shown in the diagram. It is White's move. Why do almost all serious players begin by moving either a central pawn or the king's knight? Simply because the results of millions of chess games have given these moves a better reputation than the alternatives. So you could say that White 'knows the secret' - except that after a handful of games have started with the same opening move, Black starts to realize that some ways of responding are better than others. Then White comes to know what to expect from Black.

Carry on this process over several centuries, bearing in mind that most chess positions contain a few potential moves that are just as good as one another (and some that are not as good but that might just throw an opponent off guard), and you will end up with enough opening theory to fill several encyclopedias. The question is who can remember the most.

## Using this wikibook

To use this Wikibook you will need to be familiar with the rules of chess and the algebraic system of chess notation. While it is up to you how you proceed beyond that stage, most chess coaches would recommend that you gain a basic understanding of chess strategy before trying to learn any opening theory. For example, further down this page we explain that 1. e4 is a good move because it helps control the center. Why is controlling the center a good idea? That comes under chess strategy, which is discussed in the Chess Wikibook. A more detailed discussion is located in the Elements of chess strategy Wikibook.

Each page in this Wikibook corresponds to a single position, which will be shown in the diagram on that page. One or more links will appear in the main body of the text, representing possible moves in that position. Choose a move, click it, and reach a new position. You can navigate backwards by clicking on moves in the directory list that appears at the top of each page below the title.

You can use the Encyclopedia of Chess Openings (ECO) code index if you prefer to navigate to positions that way.

## White's first move

White's first move selection is usually driven by the value of controlling the center squares of the board and allowing mobility of other white pieces. Hence, 1. e4 and 1. d4 are attractive first moves as they occupy important central squares, exert control of squares on the 5th rank, and allow White's bishops to develop. Secondary consideration is to deny Black those same benefits, thus the attractiveness of 1. d4 and 1. Nf3, preventing Black from playing 1...e5 without losing the pawn outright to a capture.

Here then are White's choices. Will White play along the popular King or Queen Pawn lines? Or will White open from a flank? Perhaps White will entertain an uncommon line to throw the game into dangerous but unexplored realms.

### All possible first white moves

 Quick Navigation a4 a3 Na3 b4 b3 c4 c3 Nc3 d4 d3 e4 e3 f4 f3 Nf3 g4 g3 h4 h3 Nh3

### Encyclopaedia of Chess Openings

ECO volume A : English Opening, Benoni Defence, Dutch Defence, King's Indian Attack, Benko Gambit, Old Indian, Bird's Opening
ECO volume B : Sicilian Defence, Caro-Kann Defence, Pirc Defence, Modern Defence, Alekhine's Defence, Scandinavian Defence
ECO volume C : Ruy Lopez, French Defence, Petrov's Defence, King's Gambit, Philidor Defence, Giuoco Piano, Two Knights Defence, Scotch Game
ECO volume D : Queen's Gambit Declined, Queen's Gambit Accepted, Slav Defence, Tarrasch Defence, Grünfeld Defence, Queen's Pawn
ECO volume E : Nimzo-Indian Defence, Queen's Indian Defence, King's Indian Defence, Catalan Opening, Bogo-Indian Defence

### Statistics

Approximate chances: White win 39%, Draw 32%, Black win 29%
Estimated first move popularity:
e4 43%, d4 37%, Nf3 10%, c4 8%, g3 1%, b3 0.3%, f4 0.2%, Nc3 0.1%, b4 0.1%, all other moves less than 0.1%.

## Theory table

For explanation of theory tables see theory table and for notation see algebraic notation

1 2 3 4 5 6
Sicilian Defence e4
c5
Nf3
d6
d4
cxd4
Nxd4
Nf6
Nc3
a6
Be2
e6
=
Ruy Lopez ...
e5
Nf3
Nc6
Bb5
a6
Ba4
Nf6
O-O
Be7
Re1
b5
=
King's Indian Defence d4
Nf6
c4
g6
Nc3
Bg7
e4
d6
Nf3
O-O
Be2
e5
=
Queen's Gambit Declined ...
d5
c4
e6
Nc3
Nf6
Bg5
Be7
e3
O-O
Nf3
Nbd7
=
King's Indian Attack Nf3
d5
g3
Nf6
Bg2
c6
O-O
Bg4
d3
Nbd7
Nbd2
e5
=

## References

• Batsford Chess Openings 2 (1989, 1994). Garry Kasparov, Raymond Keene. ISBN 0-8050-3409-9.
• Nunn's Chess Openings. 1999. John Nunn (Editor), Graham Burgess, John Emms, Joe Gallagher. ISBN 1-8574-4221-0.