The term "post-9/11" refers to the period following the terrorist attacks on September 11, 2001, in the United States. These attacks, carried out by the extremist group al-Qaeda, led to significant changes in U.S. domestic and foreign policies, including heightened security measures and the implementation of the USA PATRIOT Act. In response to the attacks, the U.S. launched the War on Terror, which included military operations in Afghanistan to dismantle al-Qaeda and remove the Taliban from power. This era also saw increased surveillance and a focus on counterterrorism efforts, impacting civil liberties and international relations.