Queen's Gambit Declined - Vienna variation
1. d4 d5 2. c4 e6 3. Nf3 Nf6 4. Bg5 Bb4+
White advances the queen's pawn to d4. Black advances the queen's pawn to d5. White pushes the c-pawn to c4.
Black moves the king's pawn to e6. White develops the knight to f3. Black develops the knight to f6.
White develops the dark-squared bishop to g5. Black develops the dark-squared bishop to b4, giving check.