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

White prioritises development of their knights, sticking to the maxim to develop "knights before bishops", with the idea that they will always want to place Nc3 and Nf3, so why not play those moves first?

Black usually develops their knight next, too, and the best place for that is 3...Nf6, entering the quiet but respectable Four knights game. This is by far the main line.

None of the ways to break symmetry are very appealing. If Black would like to develop their bishop instead, there isn't a great place for it right now:

• 3...Bc5 allows 4. Nxe5, the centre fork trick. Black's knight was not really defending the e5 pawn because after 4...Nxe5 5. d4! wins back the material with a fork. Black isn't down material, but it's a small positional mistake.
• 3...Bb4 is playable, but it may be too early because White can play 4. Nd5. This move is best reserved from after White's d-pawn has moved and the bishop would pin the knight.
• Black may consider fianchettoing it instead: the sideline 3...g6 is called the Steinitz variation and prepares ...Bg7, but is slow comparing to playing ...Nf6 now and waiting to develop the bishop along the a3 to f8 diagonal in one move later.

Another sideline is the audacious 3...f5?, the Winawer defence. Black gambits the f-pawn. The mainline is 4. d4, but even taking the pawn 4. exf5 should be winning for White, though Black has some practical chances in amateur games.

For explanation of theory tables, see theory table and for notation, see algebraic notation.
1. e4 e5 2. Nf3 Nc6 3. Nc3

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Wikipedia has related information at Three Knights Game.

• Nunn's Chess Openings. 1999. John Nunn (Editor), Graham Burgess, John Emms, Joe Gallagher. ISBN 1-8574-4221-0.

• Kasparov, Garry, & Keene, Raymond 1989 Batsford chess openings 2. ISBN 0-8050-3409-9.