Chess Opening Theory/1. e4/1...e6/2. d4/2...d5

2...d5 challenges White's centre. Black would love to take dxe4: how will White answer this threat? There are four main options.

3. exd5, the Exchange variation, White takes first before they are taken. This leads to an open, symmetrical game with a reputation for being drawish. This is the most straightforward idea and was the typical approach in the 19th century.

3. Nc3, the Paulsen variation, is the main line today. White develops a knight, preparing to recapture if 3...dxe4. More commonly, Black leaves the central tension and continues with 3...Nf6 the Classical variation, inviting 4. e5 to kick the knight, or 3...Bb4, the Winawer variation, pinning the knight and inviting 4. e5 to avoid losing the pawn. Both of these lead to closed positions.

3. e5 immediately is the Advance variation. Black looks to undermine White's pawn chain with c5 and expand on the queenside. This is the most common third move for White in amateur games.

3. Nd2 is the Tarrasch variation. White defends e4 with the knight but leaves open the option of playing c3, with the trade off of blocking in White's dark square, queen-side bishop. Play may continue with 3...Nf6 4. e5, the Closed Tarrasch, or 3...c5 and trades in the centre, the Open Tarrasch. Black can also play 3...dxe4 4. Nxe4 to transpose to a Rubinstein French.

Uncommon third moves include:

• 3. Be3!?, the Alapin gambit, will answer dxe4 with f3, looking to develop quickly with Nxf3 and Bd3.
• 3. Nf3!?, the Perseus or Perseus-Carlson gambit. After 3...dxe4 White puts the knight on an outpost on e5 where it is hard to remove (because the unwitting 4...f6?? runs into 5. Qh5+ g6 6. Nxg6 hxg6 7. Qxh8).
• 3. Bd3, the Schlechter variation, defending e4 with the bishop. This is an unnatural looking move for White and Black can score tempo on the bishop after 3...dxe4 4. Bxe4 Nf6 5. Bf3.
• 3. c4?, the Diemer-Duhm gambit, not defending e4 at all.

1. e4 e6 2. d4 d5

Wikipedia has related information at Template:Sec link auto.

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