The September 11 attacks, often called 9/11, were a series of coordinated terrorist attacks carried out on September 11, 2001. Nineteen militants linked to al-Qaeda hijacked four commercial airplanes in the United States. Two of the planes were flown into the Twin Towers of the World Trade Center in New York City, causing both skyscrapers to collapse within hours.
A third plane struck the Pentagon in Arlington, Virginia, severely damaging the building. The fourth aircraft, known as United Airlines Flight 93 crash, crashed into a field in Pennsylvania after passengers attempted to overcome the hijackers, preventing further destruction.
Nearly 3,000 people were killed, making it one of the deadliest attacks on American soil. The events shocked the world and led to major changes in global security, including tighter airport screening and international counterterrorism efforts. The United States responded by launching the War on Terror, including military action in Afghanistan.
The legacy of 9/11 continues to shape international relations, security policies, and collective memory, standing as a solemn reminder of the impact of terrorism and the resilience shown in its aftermath.