1. e4 c5

The Sicilian Defence is the most popular, and statistically, best scoring, reply to 1. e4. Like the classical reply 1… e5, it attacks the d4 square, preventing white from immediately building a strong pawn centre. But unlike 1… e5, it breaks the position’s symmetry in an attempt to steal back the initiative from white. Black’s goal here is not so much defence as counterattack; in particular, black can often build an advantage and attacking chances on the queenside, while white presses the attack on the kingside. The big disadvantage, on the other hand, to 1… c5 is that, unlike 1… e5, it does not open up a diagonal to develop a bishop. This means that white may have at least a temporary advantage in development.

There are a bewildering number of variations within the Sicilian. The most common reply for white is 2. Nf3 (attacking d4 and preparing for a queen’s pawn advance), after which black usually plays 2. d6, 2. Nc5, or 2. e6. The main line is:

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

From here, black can adopt the Najdorf Variation, 5… a6, which prepares for an advance of the e-pawn to contest the centre, the Dragon Variation, 5… g6, preparing to “fianchetto” the bishop by placing it on g7 to control the long diagonal, the Classical Variation, 5… Nc6, opting for straightforward development, or the Scheveningen Variation, 5… e6, staking a small claim in the centre without the potential overextension of pawn to e5.

The other main option for white besides 2. Nf3 is 2. Nc3, usually leading to the Closed Sicilian, where white expands on the kingside without opening up the centre as in the main line.

The Sicilian Defence was first described by Giulio Polerio in his 1594 manuscript on chess and analyzed by several subsequent theorists, but it didn’t achieve the kind of popularity it enjoys today until the mid-1800s, when it featured prominently in the matches between La Bourdonnais and McDonell, as well as at the 1851 London tournament. It actually fell out of favour in the latter half of hte 19th century, and was disliked by such luminaries as Paul Morphy, Wilhelm Steinitz, and Jose Raul Capablanca. However, by the 1940s and 1950s it was on the upswing again, and it has enjoyed tremendous popularity since then.