Chess Opening Theory/1. b3/1...d5

Black's controls the centre and opens up the queenside bishop. This prevents White from playing e4 or Nc3, as the pawn will be taken or the knight kicked respectively.

2. Bb2 is the main move: developing the bishop to control the long diagonal and prevent Black from taking more space in the centre with ...e5. White often plans a set-up involving e3 and Nf3, though move orders are flexible. One idea is to challenge the d5-pawn with e3 & c4, supported by the king's bishop. In 1. b3 move order, compared to the 1. Nf3 move order, White has retained the option of set-ups involving f4. If White can't or doesn't wish to play e3, then g3 allows them to develop their king's bishop to the other flank.

1. b3 d5

Wikipedia has related information at Nimzovich-Larsen Attack.

• Eric Schiller (2002). Unorthodox Chess Openings (2nd ed.). Cardoza. ISBN 1-58042-072-9.
• Nunn's Chess Openings. 1999. John Nunn (Editor), Graham Burgess, John Emms, Joe Gallagher. ISBN 1-8574-4221-0.

• Modern Chess Openings: MCO-14. 1999. Nick de Firmian, Walter Korn. ISBN 0-8129-3084-3.