Petrov's Defense

1. e4 e5 2. Nf3 Nf6

Petrov's Defense is catalogued under ECO code C42. It is reached after 2 moves (4 half-moves): 1. e4 e5 2. Nf3 Nf6. After the last move it is White to play. White opens 1. e4. It is the defining line of the Petrov's Defense family, which has 50 catalogued lines in total. 5 deeper lines continue from here, listed below.

Position shown after the last move; White to play.