Queen's Gambit Declined - 3...Nf6
1. d4 d5 2. c4 e6 3. Nc3 Nf6
White pushes the queen's pawn to d4. Black moves the queen's pawn to d5. White advances the c-pawn to c4.
Black plays the king's pawn to e6. White develops the knight to c3. Black develops the knight to f6.