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

= Nimzo-Larsen Attack: Classical Variation =

1. d5
Black's move d5 controls the center 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.

White can respond with a variety of moves, where most of them lead to the same result, like Bb2 and Nf3.