Philidor - Steinitz variation
1. e4 e5 2. Nf3 d6 3. Bc4 Be7 4. c3
White plays the king's pawn to e4. Black plays the king's pawn to e5. White develops the knight to f3.
Black pushes the queen's pawn to d6. White develops the light-squared bishop to c4. Black develops the dark-squared bishop to e7.
White moves the c-pawn to c3.