Queen's Indian - 4.Nc3
1. d4 Nf6 2. c4 e6 3. Nf3 b6 4. Nc3
White moves the queen's pawn to d4. Black develops the knight to f6. White moves the c-pawn to c4.
Black plays the king's pawn to e6. White develops the knight to f3. Black plays the b-pawn to b6.
White jumps the knight to c3.