Queen's Gambit Declined: Vienna Variation

The Queen's Gambit Declined: Vienna Variation is a chess opening classified under ECO code D30 in the Closed & Semi-Closed Games family, arising from 1.d4 d5, including the Queen's Gambit, Slav Defense, and related systems. It is reached after 4 moves: 1. d4 Nf6 2. c4 e6 3. Nf3 d5 4. Bg5 Bb4+. The resulting position leaves white to move.