"9/11 Day," sometimes called "Patriot Day" marks the date of a series of coordinated acts of terrorism carried out by the extremist group al-Qaeda against the United States of America.

On the morning of September 11, 2001, 19 terrorists hijacked four commercial airplanes. Two of these planes were flown into the Twin Towers of the World Trade Center in New York City, causing both towers to collapse within hours. Another plane was crashed into the Pentagon in Arlington, Virginia, while the fourth plane, United Airlines Flight 93, crashed into a field in Pennsylvania after passengers attempted to regain control of the aircraft from the hijackers. In total, nearly 3,000 people lost their lives in these attacks, making it one of the deadliest acts of terrorism in history.

First responders, including firefighters, police officers, emergency medical personnel, and other rescue workers, played a crucial role in the immediate aftermath of the 9/11 attacks. They rushed into the burning buildings, often without regard for their own safety, to save lives and provide assistance to those in need.

Following 9/11, the United States and many other countries launched a global War on Terror to combat terrorism and bring those responsible for the attacks to justice. The event had a profound and lasting impact on the world, leading to significant changes in U.S. foreign and domestic policies, including the creation of the Department of Homeland Security and the implementation of various security measures at airports and other critical infrastructure sites.

To commemorate the lives lost and the heroism displayed on 9/11, many people and organizations observe September 11th as a day of remembrance and service. This day is often referred to as "9/11 Day" or "Patriot Day." People participate in acts of service, volunteer work, and other community activities to honor the memory of those who perished in the attacks and to promote unity and resilience.

The 9/11 Memorial and Museum, located at the World Trade Center site in New York City, serves as a place of remembrance and reflection, preserving the history of the attacks and honoring the victims and first responders. Additionally, the "Tribute in Light" is an annual art installation that projects twin beams of light into the sky near the World Trade Center site to symbolize the towers that once stood there.

9/11 Day serves as a reminder of the need for continued vigilance against terrorism and the importance of coming together as a community and a nation in times of tragedy.