Chess Opening Theory/1. e4/1...c5/2. Nf3/2...e6

With 2...e6, Black opens up the a3-f8 diagonal for their dark squared bishop, while also controlling the d5 square for a second time, thus Black is able to recapture on d5 with a pawn and gain further central control with pawns. This move usually leads to the Kan, Paulsen, Taimanov, or Four Knights Sicilians.

The most common move for White is 3. d4, entering the Open Sicilian, though there is also a variety of Anti-Sicilians available to White, which aim to exploit Black's 2...e6 blocking the c8 bishop.

3. c3 is the Delayed Alapin Sicilian. While similar in character to the Normal Alapin, playing c3 on the 3rd move ensures Black cannot enter various lines they would normally enter if the Alapin was played on the 2nd move.

3. c4 is the Kramnik Sicilian, aiming to enter a Maroczy Bind position with an eventual ...d4, though this can also lead to various transpositions to the English Opening if White does not play d4.

3. b3 is the Westerinen Attack (Delayed Snyder Attack) which aims to take advantage of the fact that in the normal Snyder, Black usually plays e5 in one move to block the bishop, and with e6 already played, Black would lose a tempo playing this move.

3. Nc3 is also possible, just like when Black played 2...d6 or 2...Nc6, in which White remains flexible on when to eventually execute a d4 push. In many cases, White might wait for Black to play Nc6 before playing d4, this way White can avoid some lines like the Kan Sicilian.

Finally, White can also enter a King's Indian Attack-type position with 3. d3, 3. Qe2, or 3. g3. The King's Indian Attack in the Sicilian tends to be most effective when Black has already committed to e6, as various lines in the normal KIA (starting with 1. Nf3) are avoided, such as early Bf5 and Bg4. As a result, White argues that playing a KIA is quite useful when Black already played 2...e6. These moves are often used by players with White if they play Bb5 against both 2...d6 and 2...Nc6, as against 2...e6, Bb5 is not very effective, since it doesn't come with either check or an attack against a c6-knight.

1.e4 c5 2.Nf3 e6

Wikipedia has related information at Sicilian Defence.

• Kasparov, Garry, & Keene, Raymond 1989 Batsford chess openings 2. ISBN 0-8050-3409-9.