Terrorism is defined as the use of actual or threatened violence to create fear and alarm. The use of terrorist tactics and the percentage of incidents involving fatalities have increased in a small number of countries which experience a disporprotionate share of the world's terrorism. These countries have modern, nontotalitarian, and comparatively affluent societies. In the 1980's, terrorism is likely to persist as a mode of political expression, of gaining international attention, and of achieving limited political goals. Among the causes will be ideological conflicts, which may become more severe as shortages of critical resources (i.e., oil) constrain economic growth. Ethnic nationalism, religious fanaticism, and concern over specific issues -- such as nuclear energy and pollution -- may provide other stimulants for terrorist actions. Terrorists' tactics may change as the public tires of continuing media coverage. They may aim to exploit modern societies' vulnerabilities by threatening to use nuclear weapons, to poison water supplies, or to other chemical or biological weapons. Terrorists may also advocate large-scale, indiscriminate violence. In response to terrorism, governments and the private sector are devoting increased resources to internal security; the private security sector is growing at a rapid rate; and the number of inner perimeters encircling airports, government buildings, and corporate headquarters is increasing. No references are included.