Key ideas
- 3...g6 is the main reply. White either castles and plays Re1 and c3 to prepare d4, or exchanges at once with 4.Bxc6 dxc6 5.d3 and follows with h3, Nc3, Be3 and Qd2, often aiming for Bh6 to trade Black's fianchettoed bishop.
- 3...e6 is the main alternative. Black keeps the option of recapturing on c6 with the b-pawn and playing ...d5, and often plays ...Nge7 and ...a6 to question the bishop.
- After Bxc6 dxc6, Black has the bishop pair and an open d-file, while White has the healthier pawns and a mobile kingside majority. After ...bxc6 instead, Black keeps more central pawns and aims for ...d6 and ...e5, or ...d5.
- The c6 knight still eyes d4, so ...e5 to take the square and ...Nd4 to swap White's knight are standard ideas when the bishop stays on b5.
Plans for White
Decide early whether to take on c6. With Bxc6, play slowly against the doubled pawns and keep Black's bishops quiet with a closed centre. Without it, prepare c3 and d4 to open the centre while ahead in development.
Plans for Black
Make the exchange on c6 cost White something. Develop quickly, use the bishop pair and the d-file after ...dxc6, and build a solid centre with ...e5 and ...Nf6-d7, which also supports ...f6 or ...f5 later.
For the wider picture, see the Sicilian Defense guide.