The attacks on September 11 occurred in 2001, when terrorists from the extremist group al-Qaeda hijacked four commercial airplanes, crashing them into the World Trade Center and the Pentagon. This tragic event resulted in the deaths of nearly 3,000 people and prompted a global response, leading to the U.S. invasion of Afghanistan and the broader War on Terror. The attacks had profound impacts on U.S. domestic and foreign policy, leading to heightened security measures, changes in immigration policies, and the establishment of the Department of Homeland Security. The cultural and psychological effects also significantly reshaped American society and international relations in the years that followed.