The Queen's Gambit Accepted (QGA) is a chess opening beginning with the moves:
:1. d4 d5
:2. c4 dxc4
The Queen's Gambit Accepted is the third most popular option on Black's second move, after 2...e6 (the Queen's Gambit Declined) and 2...c6 (the Slav Defense). As Black's 2...dxc4 surrenders the centre, White will try to seize space in the centre and use it to launch an attack on Black's position. Black's game is not devoid of counterchances, however. If White's centre pawns can be held at bay, Black will try to weaken them to gain an advantage in the ensuing endgame by playing ...c5 and ...cxd4 at some stage. If White responds with exd4, the result will be an isolated pawn on d4 – which can also lead to a keen middlegame battle. If White recaptures with a piece at d4 instead, the centre will be liquidated and a fairly even game will usually ensue.
The Queen's Gambit is not considered a true gambit, in contrast to the King's Gambit, because the pawn is either regained, or can only be held unprofitably by Black. Black usually allows the pawn to be recaptured and uses the time expended to play against White's centre.
The Encyclopaedia of Chess Openings (ECO) classifies the Queen's Gambit Accepted under codes D20 to D29.
History
While the Queen's Gambit Accepted was mentioned in literature as early as the 15th century, it was the World Chess Championship 1886 between Wilhelm Steinitz and Johannes Zukertort which introduced the first modern ideas in this opening. Black's play had, until then, centred on holding on to the c4-pawn. Steinitz's plan was to return the pawn, but inflict White with an isolated pawn on d4, then play to exploit the weakness.
Even with the modern treatment, the opening suffered from a slightly dubious reputation in the early 20th century, even as Alexander Alekhine introduced further ideas for Black and it was played at the highest levels, beginning in the 1930s, though becoming less popular after World War II, as the Indian Defenses were heavily played. At the end of the 1990s, a number of players among the world elite included the Queen's Gambit Accepted in their repertoires, and the line is currently considered sound.
Main line: 3.Nf3
After 1.d4 d5 2.c4 dxc4, the most popular move is 3.Nf3, which is where the main lines of the Queen's Gambit Accepted begin. Black's most common response is 3...Nf6, though 3...a6, the Alekhine Variation, is a common sideline.
3.Nf3 prevents Black from striking at the centre with ...e5, a common third move for Black after 3.e4 and 3.e3. White delays measures to regain the pawn for the moment; the recovery of the pawn will usually be done through 4.e3 and 5.Bxc4.
Classical Variation: 3...Nf6 4.e3 e6 5.Bxc4 c5 6.0-0 a6
This is the traditional continuation after 3.Nf3, reached in thousands of games. Black has played to challenge the d4-pawn, and prepared for ...b5, which wins time by harassing the bishop on c4. In the meantime, White has safeguarded the king and regained the pawn. At this point, there are several options available for White, who needs to consider whether or not to deal with the positional threat of ...b5.
Old main line: 7.Qe2
Theory holds that Black can equalise against the old main line, 7.Qe2, which allows 7...b5 (the most common move), though Black also has the seventh move alternatives 7...Nc6 (preferred by Salo Flohr) and 7...cxd4. After 7...b5, White must retreat the bishop by playing either 8.Bb3 or 8.Bd3. After 8.Bb3, Black usually plays 8...Bb7, with the typical continuations 9.Rd1 Nbd7 10.Nc3 and 9.a4 b4 (or 9...Nbd7). After 8.Bd3, Black's most common reply is 8...cxd4.
After 7.Qe2 b5 8.Bb3 Bb7 9.Rd1 Nbd7 10.Nc3, 10...Bd6 is the Smyslov Variation, with White typically replying with 11.e4, though more common are the queen moves 10...Qb8, 10...Qb6, and 10...Qc7. White most often responds with 11.d5 to all of these.
Retreat line: 7.Bb3
A modern line is the retreat 7.Bb3, so that 7...b5 can be met with 8.a4, while 7.a4, stopping ...b5 at the cost of weakening the b4-square, is also popular, and was played by Mikhail Botvinnik in his 1963 match with Tigran Petrosian. The main line continues 5.Bxc4 e6, usually leading to a solid position, though the game can become sharp if White immediately attempts to exploit the weakness of Black's queenside in the line 6.Qb3 Bxf3 7.gxf3 Nd7 as Black gains great piece activity and spoils White's kingside pawns in return for sacrificing a pawn.
Two Knights Variation: 4.Nc3
4.Nc3 leads to the Two Knights Variation, which is a true gambit line since White can no longer expect to regain the c4-pawn after 4...a6 5.e4 b5. White's compensation in the form of a strong centre leads to immensely complicated play. Black does not need to enter this line, and 4...Nc6, 4...e6, and 4...c6 tend to transpose to the Chigorin Defense, QGD Vienna Variation, and Slav Defense respectively.
3.Qa4+
The queen check by 3.Qa4+ Nc6 4.Nf3 will quickly regain the pawn with Qxc4, but the early development of the queen allows Black to win time by harassing it, so this line is rarely played.