Friction is what keeps us from realizing our goals. It is what compromises all of our plans, sometimes making them unrecognizable. It defies our wish for perfection and constantly surprises us with new elements of resistance. It constitutes the divide between dream and reality.But friction is also what gets us moving, a necessary incentive to achieve progress. Nothing can start if it cannot push off something else. By blocking or delaying the easy solution, friction makes for a richer, more varied world. If it stops schemes from being completely fulfilled, it also stops them form going totally awry.To the modernist project, with its one-sided rationalist pretensions, friction is unambiguously bad?and so it is being disposed of at an increasing speed. The currency markets are one example, cyberspace another. This means less and less time to pause and rethink, while the vulnerability of societies is aggravated. In The Necessity of Friction, scholars tackle this topical and important concept. A number of scientific fields are engaged: physics, philosophy, economics, architecture, organizational theory, artificial intelligence, and others. Together, these contributions form the first modern-day attempt at analyzing the intriguing yet elusive subject of friction as metaphor.