Queen's Gambit Declined

With 2...e6 Black declines the c4 pawn and props up d5 with another pawn. This frees the f8-bishop but shuts the c8-bishop behind the e6 pawn. That bishop is the central strategic issue of the opening. White tries to exploit its passivity, while Black looks to activate it, exchange it, or show that it still has a defensive job to do. The defense has long been regarded as among the most dependable answers to 1. d4.

The d5/e6 pawn chain gives Black a firm share of the center. Black rarely plays ...dxc4 for free, since that hands White the center. The capture usually waits until White has spent a move on Bd3, so the bishop has to move a second time to recapture. Much of the Orthodox play turns on White completing every other useful developing move before committing the bishop. Black's main freeing break is ...c5, which often leaves one side with an isolated queen's pawn or hanging pawns, balanced by active piece play.

3. Nc3 is by far the most common continuation, followed by 3. Nf3 and 3. cxd5. 3. e4, the Diemer-Duhm Gambit, is a rare sideline. After 3. Nc3 Nf6 White chooses between three plans. 4. Bg5 was the twentieth-century main line, leading to the Orthodox Defense, the Tartakower and Lasker systems and the Cambridge Springs. 4. cxd5, the Exchange Variation, fixes a structure in which White plans either a minority attack with b4-b5 or a central advance with Nge2, f3 and e4. 4. Nf3 gives the Three Knights, where Black can answer with the Ragozin, Vienna, Semi-Slav or Semi-Tarrasch. Black also has third-move alternatives such as 3...c5 (Tarrasch), 3...c6 and 3...Be7 (Alatortsev). The position is often reached by transposition, notably 1. d4 Nf6 2. c4 e6 3. Nf3 d5, a move order White uses to sidestep the Nimzo-Indian.

The engine rates the starting position as close to balanced, with White slightly ahead, and in practice White scores a little better than Black. The opening became especially popular in the early twentieth century. In the 1927 world championship match between Alekhine and Capablanca, all but two of the 34 games opened with it. It has remained a staple at the highest level; Anand used the Lasker Variation to win the deciding game of the 2010 title match against Topalov.