B31 Sicilian Defence: Rossolimo

ECO code B31 covers the Rossolimo Variation of the Sicilian Defence after 1.e4 c5 2.Nf3 Nc6 3.Bb5 g6, where Black prepares ...Bg7 to put the bishop on the long diagonal. White's main choice is 4.Bxc6, giving up the bishop to damage Black's pawns. After 4...dxc6 Black gets an open d-file, and White often follows with d3, h3 and Nc3 to stop ...Bg4 and aim for a later f4. After 4...bxc6 Black keeps more central pawns. White can also castle first with 4.O-O Bg7 and then choose 5.Re1, supporting e4, or 5.c3, preparing d4.