A game that begins with 1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 is called the "Italian Game Two Knights Defense." It’s named this way because both knights are developed facing each other as Black plays Nf6. If White continues with 4.Ng5, this is called the "Knight Attack."
At this point, Black should be careful because if Black does not respond properly, White can play Nxf7, creating a fork that simultaneously attacks the queen on d8 and the rook on h8.
Most beginners who are not prepared for this fork end up losing their rook early in the game. In some cases, Black might move their queen to e7 to defend the f7 square. However, in this situation, White can play Bxf7, forcing Black’s king to move. This allows White to disrupt Black’s castling rights and capture a pawn, achieving two benefits with one move.
So, what’s the correct response for Black? It’s 4...d5, followed by 5.exd5. By moving the pawn on the d-file, Black blocks White’s bishop, and after White captures the d5 pawn, White’s bishop is still blocked, which makes this the most basic response for Black.
There are also other ways Black can respond. If time allows, I’ll return with a second part to discuss more advanced responses to the Knight Attack.
If you notice any errors, please let me know! :)