Despite confusing and complicated forms of terrorism, the tactics generally used by terrorists include bombing, arson, hijacking, ambush, kidnapping, and hostage taking. The terrorist is typically viewed as universally leftist, but rightist groups such as militias and special interest groups cause most of the damage in the United States. Terrorist groups collect information on potential targets through open source information, human intelligence collection, signal intelligence collection, target surveillance, and photographic intelligence collection. Although the general public may continue to view the terrorist as a foreigner who entered the United States, the terrorist is often an angry U.S. worker who has been fired and seeks revenge. The U.S. Department of Justice estimates that almost 1 million workers are victims of violence on the job each year. Corporations and workers spend almost $4 billion yearly to cover the costs of lost wages, property damage, theft, and legal and medical expenses. An industry has developed in the 1990's to help corporations battle the problem of worker violence, with books, videos, and seminars are available to help companies. Polaroid Corporation, for example, has trained staff managers in how to recognize signs of possible worker violence. Advanced warning combined with advanced security measures are essential in preventing terrorism. Advanced warning may be achieved by magnetically encoded photo identification cards restricting employee access to essential floors only, steel-wrapped columns for increased infrastructure, and outdoor parking. Several key terrorist incidents are described, such as the World Trade Center bombing, activities of the Unabomber, the Waco incident, and the Oklahoma City bombing. Antiterrorism legislation is discussed, including the Comprehensive Anti-Terrorism Act of 1995 and the Comprehensive Terrorism Prevention Act of 1995. 28 references