The series of terrorist attacks referred to as September 11th occurred in the year 2001.
On the morning of Tuesday, September 11, 2001, 19 militants associated with the extremist group al-Qaeda hijacked four commercial airplanes. Two of the planes were crashed into the North and South Towers of the World Trade Center complex in New York City. A third plane was crashed into the Pentagon in Arlington, Virginia. The fourth plane, after a passenger revolt, crashed into a field in Shanksville, Pennsylvania, short of its intended target in Washington, D.C.
The key term for this event, "September 11th" (or "9/11"), functions grammatically as a proper noun. It has evolved from a simple calendar date into a specific name that designates the attacks, their immediate aftermath, and their profound historical significance. As a proper noun, it serves as a unique identifier for a defining moment in modern history, encapsulating the events and consequences of that day.
