It is traditionally described as a gambit because White appears to sacrifice the c-pawn; however, this could be considered a misnomer as Black cannot retain the pawn without incurring a disadvantage.
[5] As Wilhelm Steinitz and Siegbert Tarrasch developed chess theory and increased the appreciation of positional play, the Queen's Gambit grew more popular,[5] reaching its zenith in the 1920s and 1930s, and it was played in all but 2 of 34 games in the 1927 World Championship match between José Raúl Capablanca and Alexander Alekhine.
In the QGA, Black plays 2...dxc4, temporarily giving up the center to obtain freer development.
Technically, any Black response other than 2...dxc4 (or another line with an early ...dxc4 that transposes into the QGA) is a Queen's Gambit Declined, but the Slav, Albin Countergambit, and Chigorin Defense are generally treated separately.
After 1.d4 d5 2.c4: If White chooses to fianchetto the king's bishop, the game transposes into the Catalan Opening.