What is al qaeda and why is it such a threat?

Al-Qaeda is a militant Islamist organization founded in the late 1980s by Osama bin Laden and others, originally to support the mujahideen in Afghanistan. It seeks to establish a global Islamic caliphate and has carried out numerous high-profile terrorist attacks, including the September 11, 2001 attacks in the U.S. Its decentralized structure allows it to operate through affiliated groups worldwide, making it difficult to combat and posing a persistent threat to international security and stability. Al-Qaeda's extremist ideology and ability to inspire lone-wolf attacks further amplify its danger.