On the morning of September 11, 2001, the entire world was introduced to Al Qaeda and its enigmatic leader, Osama bin Laden. But the organization that changed the face of terrorism forever and unleashed a whirlwind of counterterrorism activity and two major wars had been on the scene long before that eventful morning. In this text, Daniel L. Byman, an eminent scholar of MiddleEast terrorism and international security who served on the 9/11 Commission, provides a sharp and concise overview of Al Qaeda, from its humble origins in the mountains of Afghanistan to the present, explaining its perseverance and adaptation since 9/11 and the limits of U.S. and allied counterterrorism efforts.