Chess Opening Theory/1. d4/1...d5/2. c4/2...c6/3. cxd5/3...cxd5/4. Nc3/4...Nf6

The most common move for Black. White now has to reveal their opening plan.

5. Bf4 is the most common move, delaying Nf3 and developing the bishop.

5. Nf3 is the second-most common move. This allows a completely equal position and is often used if playing for a draw, especially the variation 5...Nc6 6. Bf4 Bf5 7. e3 e6 8. Bd3 Bxd3 9. Qxd3 Bd6 10. Bxd6 Qxd6 =

5. f3 is the Boor attack, a rare sideline where White tries to take over the center by preparing e4.

After both 5. Bf4 and 5. Nf3 Black can try to continue copying their opponent or break the symmetry with the waiting move 6...a6 (played after 5...Nc6). This is a multi-purpose move: it prevents White's light-squared bishop from developing to b5, pinning the knight, and it is useful as a waiting move. If White plays both Nf3 and e3, Black can usefully develop the light-squared bishop to g4 where it pins White's knight to the queen.

1. d4 d5 2. c4 c6 3. cxd5 cxd5 4. Nc3 Nf6

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