Catalan Opening: Open Defense, Classical Line

The Catalan Opening: Open Defense, Classical Line is a chess opening classified under ECO code E05 in the Indian Defences family, where Black responds to 1.d4 with 1...Nf6, including the Nimzo-Indian, Queen's Indian, and King's Indian. It is reached after 6 moves: 1. d4 Nf6 2. c4 e6 3. Nf3 d5 4. g3 Be7 5. Bg2 O-O 6. O-O dxc4. The resulting position leaves white to move.