The Sicilian defence is a chess opening which begins with:

1. e4 c5

This is the most popular response to 1. e4 at the master level. Black immediately fights for the center, but by attacking from the c-file (instead of mirroring White's move) he creates an asymmetrical position that leads to lots of complicated situations. Typically, White has the initiative on the King side while Black obtains counterplay on the Queen side, particularly on the c file after the exchange of Black's c pawn for White's d pawn.

Dragon

8 7 6 5 4 3 2 1 a b c d e f g h

Black can adopt a variety of set-ups, among them the Dragon variation, which begins

1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 g6

In this variation, Black fianchettos a Bishop on the h8-a1 diagonal. This is called the "Dragon" variation because Black's pawn structure is supposed to look like a dragon. Another reason for the name could be that a very aggressive middlegame usually develops following opposite side castling. This is especially true of the Yugoslav Attack, an aggressive system featuring pawn storms on opposite sides of the board. White tries to break open the Black kingside and deliver mate down the hfile, while black seeks counterplay on the queenside with sacrificial attacks, rook sacrifices on c3 are often thematic and strong. Main exponents of the dragon include Gufeld, Topalov, Soltis, Mestel, Miles and Ward. Kasparov used the dragon with success as a surprise weapon against world title challenger Vishy Anand.

Najdorf

8 7 6 5 4 3 2 1 a b c d e f g h

Another popular system is the Sicilian Najdorf, which begins

1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 a6

White plays a variety of moves here, including 6. Bg5, 6. Be2, 6. Be3, and Bobby Fischer's preferred response, 6. Bc4.

Other systems

Black can adopt a number of other set-ups, including the Scheveningen (1. e4 c5 2. Nf3 e6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 d6) and the Sveshnikov (1. e4 c5 2. Nf3 Nc6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 e5), which as of 2003 is very fashionable at the top level.

To avoid giving Black this choice of systems, White can adopt a number of so-called "anti-Sicilian" lines, including 2. Nc3 (the Closed Sicilian) and eventually the Yugoslav, 2. c3 (the Alapin Sicilian), 2. d4 cxd4 3. c3 (the Smith-Morra Gambit), lines with an early f4 (the Grand Prix Attack) and various lines with an early Bb5.