Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Nc3/3...f5

=Winawer Defense=

3...f5
The Winawer Defense, also known as the Gothic Defense, is an excellent response by Black instead of transposing into a Four Knight's Game. Black gambits the pawn on f5; if white accepts, the gambit creates an equalizing position for black and black often plays 4...Nf6.

Theory table
'''1. e4 e5 2. Nf3 Nc6 3. Nc3 f5'''