As incidents of terrorism have increased in the past decade, the phenomenon of terrorism has become of concern to governments and of increasing interest to scholars. The term "terrorism" has no precise or widely-accepted definition. The problem of defining terrorism is compounded by the fact that terrorism has recently become a fad word often applied to a variety of acts of violence which are not strictly terrorism. The paper defines terrorism and cites examples of international terrorist events. Problems discussed include deciding whether to consider activities of separatist groups, violence carried out by terrorists operating within their own country, individual hijackings, and bombings as instances of terrorism. The Rand chronology of terrorist activities has been a useful tool in assessing the magnitude of the terrorist problem. Results have shown that the level of international terrorism perceived by the public is frequently determined by the quality of the incidents, location, and degree of media coverage, not by the level of violence.