This article discusses the historical evolution and the causes of the terrorism as a form of political violence, by looking at the changing ideology, organization and structure, as well as motives and roots. First, the article examines the historical evolution of the terrorism, together with its goals and motivation. Second, it brings up the difficulties for defining terrorism by emphasizing historical and current challenges. In this part, the main pillars of the common definitions are also presented. Third, the last part of the article is dedicated to explain the main causes of the terrorism, with special attention to contextual, convictional, motivational and facilitating causes.