Chess Opening Theory/1. e4/1...c5/2. Nf3/2...d6/3. Bb5

=Open Sicilian= Moves: 1. e4 c5 2. Nf3 d6 3. Bb5+

The move Bb5+ is considered an Anti-Sicilian, and is the most commonly seen thereof. White develops his bishop with a tempo, enabling kingside castling, and may seek to develop rapidly along similar lines to the Ruy Lopez in order to meet Black's later attack head-on, or simply to control d5 by playing c4 but, not wishing to have the king's bishop stuck behind the c4 pawn, exchanging it off first. However, Black's own development can carry on unhindered and he tends to get an equal game - trying to sabotage the Sicilian this early on may be a cure worse than the disease.

Black has three replies, assuming no sentient being would block the check with the queen.
 * /3...Nc6/ leads to a Lopez-type setup in which Black has already played the useful c5;
 * /3...Nd7/ a more defensive variant of the above considered to grant White a minor advantage;
 * /3...Bd7/ wins a tempo by compelling the exchange of bishops but gives White more options.