The 157th Faraday Discussion represented a historic turning point in the development of the field of reaction dynamics because it concerned itself with how reactions occur in gases, in liquid, and at interfaces. Never before has the attempt been made to unify the various approaches to reaction dynamics in one Faraday Discussion meeting and to discover what language was common and what was special to these previously distinct subdisciplines. This Discussion also marked a maturation of the field of reaction dynamics in that so much emphasis was placed on what the combination of theory and experiment could tell us about the detailed course of chemical transformations.