terrorism

Introduction & Top Questions
Definitions of terrorism
Types of terrorism
History

References & Edit History Related Topics

Images & Videos

Rise and fall of the Red Army Faction in West Germany

Ku Klux Klan members in white robes and hoods stand in a circle at night around a large burning cross in Tennessee.

World Trade Center: jetliner approaching a tower

Thematic map of the northeastern United States showing the flight paths of the four hijacked planes during the September 11, 2001 attacks. Color-coded arrows trace the routes of American Airlines flights 11 and 77, and United Airlines flights 175 and 93, with destinations in New York City, Washington, D.C., and Shanksville, Pennsylvania. Major cities and state boundaries are labeled for context.

At a Glance

terrorism summary

Related Questions

How can harsh military responses to terrorism create a cycle of violence and support for extremists?
How did Joseph Stalin's government use terror in the Soviet Union?
How did Nazi Germany use terror to control its population?
How did Roman emperors such as Tiberius and Caligula use fear to discourage opposition?
How did Saddam Hussein's government use terror in Iraq?
How did automatic weapons and compact explosives change terrorism in the 20th century?
How did disputes over land contribute to terrorism in the Israeli-Palestinian conflict?
How did military dictatorships in Brazil Chile and Argentina use state terrorism against their populations?
How did religious conflict contribute to violence in Northern Ireland?
How did the African National Congress use subrevolutionary terrorism in its campaign against apartheid?
How did the Jewish Sicarii use violence against Roman rule and suspected collaborators?
How did the Red Brigades and the Red Army Faction fit the category of revolutionary terrorism?
How did the September 11 attacks change policing and counterterrorism efforts?
How did the meaning of the term terrorism change from the French Revolution to the 20th century?
How do terrorist groups use publicity to increase the effects of violence?
How does a suicide bombing differ from other forms of terrorist attack?
How does subrevolutionary terrorism differ from revolutionary terrorism?
How does terrorism differ from guerrilla warfare?
How were the September 11 attacks carried out?
What happened during the 1995 Tokyo subway nerve-gas attack by AUM Shinrikyo?
What happened in the 1998 bombings of U.S. embassies in Kenya and Tanzania?
What happened in the Oklahoma City bombing of 1995?
What happened in the attack on the USS Cole in 2000?
What were the effects of the September 11 attacks on the World Trade Center and the Pentagon?
Which terrorist groups were especially prominent in the late 20th century?
Why are the time and place of violence linked to stochastic terrorism difficult to predict?
Why can counterterrorism surveillance create concerns about civil liberties and police abuse?
Why can the distinction between a terrorist and a freedom fighter be controversial?
Why did police agencies increase cooperation with intelligence and national-security agencies after September 11?
Why did some anarchists in the late 19th century assassinate political leaders?
Why did the Ku Klux Klan use intimidation during Reconstruction after the American Civil War?
Why have crowded civilian places been targeted in terrorist attacks?
Why is it difficult for countries and legal systems to agree on a single definition of terrorism?
Why might terrorist groups target embassies or military installations?
What are the differences between domestic and international terrorism?
What are the types of terrorism?
What is lobbying?
Why is lobbying considered important in representative democracies?
Who was one of colonial America’s first lobbyists?
What are the two main types of lobbying?
What is bootlegging?
What is swatting?
Why is swatting difficult to prevent?
What was the outcome of the 2017 swatting incident involving Casey Viner, Shane Gaskill, and Tyler Barriss?

Politics, Law & Government Law, Crime & Punishment

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External Websites

Social Sciences LibreTexts - Terrorism
Stanford Encyclopedia of Philosophy - Terrorism
CFR Education - What Is Terrorism?
Cambridge Core - British Journal of Political Science - Terrorism and Migration: An Overview
Cornell Law Scholl - Legal Information Institute - Terrorism
PBS Frontline - The Evolution Of Islamic Terrorism
Digital History - Terrorism in Historical Perspective

Britannica Websites

Articles from Britannica Encyclopedias for elementary and high school students.

terrorism - Children's Encyclopedia (Ages 8-11)
terrorism - Student Encyclopedia (Ages 11 and up)

terrorism

society

Written by

John Philip Jenkins

Distinguished Professor of History, Baylor University. Author of A History of the United States, Mystics and Messiahs: Cults and New Religions in America, Synthetic Panics: The Symbolic...

John Philip Jenkins

Fact-checked by

Britannica Editors

Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree....

Britannica Editors

Last updated

Nov. 12, 2026 •History

terrorism, the calculated use of violence to create a general climate of fear in a population and thereby to bring about a particular political objective. Terrorism has been practiced by political organizations with both rightist and leftist objectives, by nationalistic and religious groups, by revolutionaries, and even by state institutions such as armies, intelligence services, and police. Definitions of terrorism are usually complex and controversial, and, because of the inherent ferocity and violence of terrorism,...

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