Black faces three major problems in many variations of the Queen's Gambit Declined (QGD):

• Development of the black queen bishop is difficult, as it is often blocked by ... e6.
• The pawn structure offers White targets, especially the possibility of a minority attack on the queenside in the Exchange variation of the QGD.
• White often plays Bg5 to pin the black king knight on f6 against the black queen, and unpinning it is awkward for Black.