The September 11 attacks (also referred to as September 11, September 11th, or 9/11) were a series of four coordinated terrorist attacks launched by the Islamic terrorist group al-Qaeda upon the United States in New York City and the Washington, D.C. area on Tuesday September 11, 2001.
Four passenger airliners were hijacked by 19 al-Qaeda terrorists so they could be flown into buildings in suicide attacks. Two of those planes, American Airlines Flight 11 and United Airlines Flight 175, were crashed into the North and South towers, respectively, of the World Trade Center complex in New York City. Within two hours, both towers collapsed with debris and the resulting fires causing partial or complete collapse of all other buildings in the WTC complex, as well as major damage to ten other large surrounding structures. A third plane, American Airlines Flight 77, was crashed into the Pentagon (the headquarters of the United States Department of Defense), leading to a partial collapse in its western side. The fourth plane, United Airlines Flight 93, was targeted at the United States Capitol in Washington, D.C., but crashed into a field near Shanksville, Pennsylvania after its passengers tried to overcome the hijackers. In total, almost 3,000 people died in the attacks, including the 227 civilians and 19 hijackers aboard the four planes.
Terrorism is the systematic use of terror, often violent, especially as a means of coercion. In the international community, however, terrorism has no legally binding, criminal law definition. Common definitions of terrorism refer only to those violent acts which are intended to create fear (terror); are perpetrated for a religious, political or, ideological goal; and deliberately target or disregard the safety of non-combatants (civilians). Some definitions now include acts of unlawful violence and war. The use of similar tactics by criminal organizations for protection rackets or to enforce a code of silence is usually not labeled terrorism, though these same actions may be labeled terrorism when done by a politically motivated group. The writer Heinrich Böll and scholars Raj Desai and Harry Eckstein have suggested that attempts to protect against terrorism may lead to a kind of social oppression.
The word "terrorism" is politically and emotionally charged, and this greatly compounds the difficulty of providing a precise definition. Studies have found over 100 definitions of “terrorism”. The concept of terrorism may be controversial as it is often used by state authorities (and individuals with access to state support) to delegitimize political or other opponents, and potentially legitimize the state's own use of armed force against opponents (such use of force may be described as "terror" by opponents of the state).
Terrorism has been practiced by a broad array of political organizations to further their objectives. It has been practiced by both right-wing and left-wing political parties, nationalistic groups, religious groups, revolutionaries, and ruling governments. An abiding characteristic is the indiscriminate use of violence against noncombatants for the purpose of gaining publicity for a group, cause, or individual. The symbolism of terrorism can leverage human fear to help achieve these goals.