The Sicilian Defense may be the single most common chess opening in modern play. There are countless lines that can arise from the starting moves of 1. e4 c5. Some of the most popular are discussed on the following pages, but many other lines are widely played as well.
The Sicilian Defense allows Black to attack the d4 square and fight for the center without the symmetry that results from 1. ... e5. This generally leads to unbalanced positions, and usually leaves black with a central pawn majority after trading his c-pawn for White's d-pawn.