The September 11 attacks, also known as 9/11, were a series of terrorist acts in the United States on September 11, 2001. The attacks involved the hijacking of four commercial airliners by terrorists. These planes were then deliberately flown into the World Trade Center towers in New York City and the Pentagon in Arlington, Virginia. Unfortunately, one of the planes crashed into a field in Pennsylvania. The attacks resulted in nearly 3,000 deaths, including passengers on the planes, first responders, and civilians. The impact of the attacks was felt worldwide, leading to significant changes in global security measures.