Chess Opening Theory/1. b3/1...d5/2. Bb2

White's bishop controls a swathe across the middle of the board, including the e5 square, preventing Black from building the ideal two-pawn centre.

As ...e5 is harder to achieve now, Black may consider playing with ...e6 in order to develop the king's side bishop. This would inhibit development of the queen's bishop, so Black may wish to decide on its future first.

2...Bg4 is a common plan, which pins White's e-pawn and so makes it harder for them to play e3 and free their bishop. If 3. h3 Bh5 4. g4 Bg6 5. e3, then Black has extracted the concession of a weakened kingside.

2...Bf5 is an alternative destination (or in the order 2...Nf6 & 3...Bf5). Black can adopt a reversed London system set-up with ...e6, ...c6, ...Nd7 etc.

The other plan for the king's bishop is to fianchetto it, and directly oppose White's bishop on the long diagonal. Of course Black cannot play 2...g6?? yet or blunder their rook: first they must play 2...Nf6 to prepare 3...g6.

2...c5, the more maximalist approach, is a natural move and takes more space on the flank. 3. e3 preparing Bb5 resembles Nimzo-Indian or Bogo-Indian defence in reverse

1. b3 d5 2. Bb2