This book not only covers the most-played opening in online chess, but a complementary opening system as well. It makes sense to study both the versatile London System - moving the bishop to f4 - and the more aggressive Trompowsky Attack, moving the bishop to g5. This will offer White more flexibility and deepen your understanding of both systems. It gives White the opportunity to surprise his opponent, while still playing the same opening patterns. And both openings are connected by a large number of possible transpositions.