Chess Opening Theory/1. e4/1...e5/2. Bc4/2...Nf6/3. f3/3...d5

3...d5!
This move is an aggressive response to white's passive 3. f3!? as it strikes in the center and opens up more lines for black's pieces.

White's main options are:


 * /4. exd5/ is the most popular and best option as it is an equal trade after 4...Nxd5 5. Bxd5 Qxd5.


 * /4. Bxd5/ usually transposes to the 4. exd5 line, after 4...Nxd5 5. exd5 Qxd5.


 * /4. Bb3/?! is a dubious option as it does not accept an important pawn trade as 4...dxe4 5. fxe4 and white's kingside is very weak, but this might have something with because after 5. fxe4, white still has a pawn in the center and it opens up f3 for the king's knight.


 * 4. Bb5?! checks the black king, and its purpose is almost the same as 4. Bb3.

'''1. e4 e5 2. Bc4 Nf6 3. f3!? d5!'''