 Black often delays this move in these Sicilians, trying to get some space  and play on the opposite wing first (or in the center.)
1. e2e4  1... c7c5  2. g1f3  2... d7d6  3. d2d4  3... c5d4  4. f3d4  4... g8f6  5. b1c3  5... a7a6  6. f1e2  6... e7e6  7. c1e3 