Answer:
9/11 refers to the terrorist attacks that took place on September 11, 2001, in the United States. The attacks were orchestrated by the extremist group Al-Qaeda, who hijacked four commercial airplanes. Two planes were flown into the Twin Towers of the World Trade Center in New York City, causing their collapse. Another plane crashed into the Pentagon in Arlington, Virginia, while the fourth plane, United Airlines Flight 93, crashed into a field in Pennsylvania after passengers bravely fought back against the hijackers. The 9/11 attacks resulted in the loss of thousands of lives and caused immense devastation, leaving a lasting impact on the global political landscape and leading to significant changes in security measures worldwide.
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