A chess opening characterized by the moves 1.e4 e5 2.Nf3 Nc6 3.Nc3 Nf6
The Four Knights is usually a positional opening where White obtains the two bishops. In the ensuing complications, Black aims to close the center, while White tries to open it up, to make use of his bishops.
A key turning point is the Rubinstein variation: 1.e4 e5 2.Nf3 Nc6 3.Nc3 Nf6 4. Bb5 Nd4!?
This variation sacrifices a pawn for piece activity and easier development.