The "war on terror" refers to a global campaign initiated by the United States and its allies after the September 11, 2001, terrorist attacks. The primary goal is to eliminate terrorist groups, particularly Al-Qaeda and later ISIS, that threaten national and international security. This campaign includes military action, intelligence operations, and diplomatic efforts to combat terrorism worldwide. The war on terror has led to significant military engagements in countries like Afghanistan and Iraq. It has also prompted changes in domestic security policies and international cooperation to prevent terrorist activities. Critics argue about its effectiveness and the impact on civil liberties and global stability.