Queen's Gambit Declined: Orthodox Defense, Bd3 Line

The Queen's Gambit Declined: Orthodox Defense, Bd3 Line is a chess opening classified under ECO code D66 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 8 moves: 1. d4 d5 2. c4 e6 3. Nc3 Nf6 4. Bg5 Be7 5. e3 O-O 6. Nf3 Nbd7 7. Rc1 c6 8. Bd3. The resulting position leaves black to move.