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what was 9/11

9/11 refers to a series of coordinated terrorist attacks carried out in the United States on September 11, 2001, that killed nearly 3,000 people and reshaped global politics and security policy.

What was 9/11?

On the morning of 11 September 2001, 19 terrorists linked to the extremist group al‑Qaeda hijacked four commercial passenger planes departing from U.S. airports. Their plan was to turn these fuel‑heavy aircraft into weapons by crashing them into major symbolic targets in the United States.

  • Two planes were flown into the Twin Towers of the World Trade Center in New York City, causing both 110‑story towers to collapse within about two hours.
  • A third plane was crashed into the Pentagon, the headquarters of the U.S. Department of Defense, near Washington, D.C.
  • The fourth plane, United Flight 93, crashed in a field in Pennsylvania after passengers tried to overpower the hijackers; investigators believe it was likely aimed at either the White House or the U.S. Capitol.

Key facts in brief

  • Date: 11 September 2001.
  • Perpetrators: 19 hijackers associated with al‑Qaeda, an Islamist extremist organization led at the time by Osama bin Laden.
  • Main targets:
    • World Trade Center (New York City) – Twin Towers.
* Pentagon (near Washington, D.C.).

* Presumed target of Flight 93: U.S. Capitol or White House (never reached).
  • Deaths: About 2,977 victims in the attacks, plus the 19 hijackers.
  • Nature of attack: Coordinated suicide hijackings using commercial airliners as weapons.

How the day unfolded (very short timeline)

  • Around 8:46 a.m.: American Airlines Flight 11 hits the North Tower of the World Trade Center.
  • 9:03 a.m.: United Airlines Flight 175 hits the South Tower.
  • 9:37 a.m.: American Airlines Flight 77 crashes into the Pentagon.
  • 9:59 a.m.: The South Tower collapses.
  • 10:02 a.m.: United Flight 93 crashes in a field in Pennsylvania after passengers resist the hijackers.
  • 10:28 a.m.: The North Tower collapses.

Why 9/11 matters today

9/11 is widely seen as one of the most significant events in modern history, especially for the United States and its foreign policy. It led to the “War on Terror,” U.S.‑led military operations in Afghanistan and later Iraq, major changes in airport and domestic security, and long‑lasting debates about civil liberties, surveillance, and counter‑terrorism.

Each year, memorial ceremonies are held, and museums and archives preserve records and personal stories to remember the victims and the first responders who tried to save lives. The attacks continue to be discussed in news, classrooms, and public forums as people reflect on their causes, consequences, and how they shaped the 21st century.

TL;DR: 9/11 was a coordinated set of terrorist hijackings on 11 September 2001 in which four planes were turned into weapons, destroying the Twin Towers, damaging the Pentagon, killing nearly 3,000 people, and triggering huge global political and security changes.