A useful to move to gain space and keep the bishop on the g1-a7 diagonal.
1. e2e4  1... e7e5  2. g1f3  2... b8c6  3. f1b5  3... g8f6  4. d2d3  4... f8c5  5. e1g1  5... c6d4  6. f3d4  6... c5d4  7. b1d2  7... c7c6  8. b5c4 A rare move. 8.Ba4 is much more popular. 8... d7d6  9. c2c3  9... d4b6  10. c4b3 