King's Knight Opening

The most common second move in the open games. The knight attacks e5 at once, and most of the classical openings — the Ruy Lopez, the Italian Game, the Scotch, the Petrov — begin here.

It is reached after 3 moves: 1. e4 e5 2. Nf3.

Black is to move and has 29 legal moves. Over the next four moves — two for each side — the game can branch into 665,063 different games. Those games reach 229,658 different positions: most positions can be reached in more than one way, 2.9 on average.

The Lichess opening list names 693 further lines after this position, such as Petrov's Defense (2... Nf6) and Philidor Defense (2... d6).

The same moves can be played in 2 different legal orders that all reach this position. For example 1. Nf3 e5 2. e4, which starts as the Zukertort Opening.