What to know about the 9/11 attacks

Exactly 24 years ago today, on September 11, 2001, the world witnessed one of its most devastating terrorist attacks. Nearly 3,000 people were killed, countless others injured, multiple buildings were destroyed, and the global order was altered forever.

To Americans, and many others around the world, it is worth remembering not just the 9/11 attacks themselves, but also how those events reshaped security, society, and collective memory.

In this article, Tribune Online takes a look at some essential things to know about the 9/11 attacks.

Scale and coordination of the attacks

Nineteen terrorists affiliated with the extremist group al-Qaeda hijacked four commercial airplanes. Two were flown into the Twin Towers of the World Trade Center in New York City, one into the Pentagon in Washington, D.C., and the fourth (United Flight 93) crashed in a field in Shanksville, Pennsylvania, after passengers attempted to retake control.

Massive loss of lives and destruction

Almost 3,000 people were killed in the attacks. The destruction included not only the World Trade Center towers but also several other buildings in the WTC complex, extensive damage to the Pentagon, and massive infrastructural and economic losses.

Collapse of the Twin Towers

The Twin Towers were hit by hijacked planes (North Tower at about 8:46 a.m., South Tower at about 9:03 a.m.). The fires sparked by the crashes weakened structural supports, and both towers collapsed (South Tower first, then North Tower) within two hours of impact.

United Flight 93’s resistance

Passengers on United Flight 93, after learning about the other attacks, attempted to resist the hijackers. Because of their actions, the plane crashed in Pennsylvania rather than reaching what was believed to be another high-profile target. Their bravery prevented further destruction.

The role of al-Qaeda and its leadership

The attacks were planned and executed by al-Qaeda, an Islamist extremist group founded by Osama bin Laden. The 9/11 attacks were part of its strategy targeting the United States, which the group considered an enemy because of its foreign policy in the Middle East.

Investigation and the 9/11 Commission

In the aftermath, the U.S. government created a bipartisan body, the 9/11 Commission, to examine how and why the attacks happened, what intelligence or security failures enabled them, and what should be done to prevent similar incidents. The commission’s final report, released in 2004, made numerous recommendations.

Changes to U.S. and global security policy

9/11 led to sweeping changes in how governments approach security: tightened airport screening, the creation of the U.S. Department of Homeland Security, greater intelligence sharing between countries, and laws such as the USA PATRIOT Act. Many nations around the world also reassessed their counterterrorism measures.

Health and environmental impacts

Responders and survivors of the attacks faced significant health consequences, including respiratory illnesses, PTSD, and other long-term conditions caused by exposure to dust, smoke, and toxic materials at Ground Zero.

Memory, memorials, and culture

The date is remembered in many ways: memorials in New York (the 9/11 Memorial & Museum), at the Pentagon, and in Pennsylvania. Cultural works such as books, films, and art have kept the memory alive. Public remembrances often include reading the names of victims, moments of silence, and media coverage reflecting on lessons learned. In the United States, Patriot Day is observed every 11 September to honour the victims who lost their lives in the attacks.