Nimzo-Indian - 4.e3 c5

White pushes the queen's pawn to d4. Black develops the knight to f6. White moves the c-pawn to c4.

Black pushes the king's pawn to e6. White develops the knight to c3. Black develops the dark-squared bishop to b4.

White advances the king's pawn to e3. Black pushes the c-pawn to c5.