The Queen’s Gambit Declined is one of the central pillars of chess opening theory. Virtually every world champion has played the opening with both the white and black pieces and it is a great favorite at all levels in chess. The reason for its enduring popularity is that it is rich in the classic strategic themes. Either side can end up with an isolated d-pawn, White can pursue a queenside initiative while Black counters on the other wing or White can attempt to build a powerful centre that Black hopes to undermine.