Chess Opening Theory/1. d4/1...d5/2. c4/2...e6/3. Nc3/3...Nf6

With 3...Nf6 Black begins developing the minor pieces, fighting for the center and gets closer to castling.

This is the classical main-line of the Queen's Gambit Declined. White has several options, though some of these may transpose into each other at some point.

4. cxd5 is the exchange variation. Unlike other exchange variations notorious for yielding a quiet game (e.g. French, Slav), this exchange results in what is known as the Carlsbad pawn-structure, which has several aggressive plans including the "minority attack" on the queenside or a preparation for an all-out assault by seizing the center with an eventual e2-e4 or e3-e4.

4. Nf3 is the solid classical option. White gives Black many choices on how to continue development, including some of the most aggressive variations of the Queens gambit declined.

4. Bg5 leads to another wide variety of positions, often quite different from the ones resulting from 4. Nf3. White gets the dark-squared bishop outside of the pawnchain in order to be able to release the light-squared bishop with e2-e3. Black usually unpins the knight with 4...Be7 and tries to castle quickly, after which they are faced with the choice between some of the most well-studied openings in the Queen's gambit.

1. d4 d5 2. c4 e6 3. Nc3 Nf6

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