The historical analysis of terrorism not only describes the nature of terrorism from ancient to modern times, but also explores the mentality of its foremost perpetrators. A survey of global trends covers numbers of incidents and locations, types of attacks, victims' characteristics, and differences between left and right-wing terrorists. The strategies and tactics of three types of terrorist groups are reviewed: nationalist-separatist movements, ideological extremists and nihilists, and issue-oriented groups who resort to terrorism when extremely frustrated. The paper examines the social causes of terrorism, focusing social change accelerated by modernization. Also discussed are terrorists' psychological characteristics and motivations. A section on prevention and control addresses legal issues and international response, target hardening, identifying terrorists' likely targets, media coverage, intervention, and negotiation. Finally the paper examines terrorists' impact on their victims and future trends. Approximately 75 references.