The London System, which for a long time had the reputation of a rather harmless sideline, has developed into a very popular opening, and World Champion Magnus Carlsen is only one of many top players who play it regularly. The London System indeed suits the modern approach to openings very well: White does not necessarily strive for an opening advantage but is content to develop his pieces and hopes to outplay his opponent in the middlegame. However, the London System is more dangerous than it seems and if Black is not careful he can easily wind up in a bad position. Theory develops fast today, even in less concrete systems.