Chess Opening Theory/1. e4/1...Nc6/2. Nf3

White develops their knight to its most active square, and offers to let Black transpose into the Open Game. This avoids the original positions resulting from lines like 2. d4 d5 3. e5 Bf5.

To keep things in original territory, Black may play 2...d6, the Williams variation, or 2...f5?!, the Colorado gambit.

Black can transpose into the Open Game, usually reached after 1. e5 e5 2. Nf3 Nc6, with 2...e5, but other transpositions are inferior because of the placement of Black's knight.

• 2...d5 leads to a sort of Scandinavian defence, where Black's knight prevents the useful move pawn to c6.
• 2...e6 leads to a French defence where Black cannot play ...c5.
• 2...g6 leads to an irregular Modern.

'1. e4 Nc6 2. Nf3'

Wikipedia has related information at Nimzowitsch Defence.

• Kasparov, Garry, & Keene, Raymond 1989 Batsford chess openings 2. ISBN 0-8050-3409-9.