A standard maneuver. The knight opens the  road for the f-pawn.
1. e2e4  1... c7c6  2. d2d4  2... d7d5  3. e4e5 A solid choice in the final game. 3... c8f5  4. g1f3  4... e7e6  5. f1e2  5... g8e7  6. c2c3  6... h7h6  7. e1g1  7... b8d7  8. a2a4  8... a7a5  9. b1a3  9... f5h7 