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

= Three Knights Game = Black can copy White's moves with /3...Nf6/, leading to a very quiet game.

Other alternatives include bishop moves:
 * /3...Bb4/ is playable, but it may be too early because White can play 4. Nd5 (the knight is not pinned yet).
 * /3...Bc5/ is dangerous because White can play 4. Nxe5; after 4...Nxe5, White can play 5.d4, winning back the material with a fork. However, it's not really a mistake, because Black will be able to take a pawn during the process. In this line, 4...Bxf2+ is playable and does not lose material.

It's also possible to play /3...g6/. It may prepare f5. It may also transpose into Scotch Game as the d4 counterattack is often seen.

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