Al-Qaeda is a violent Islamist group that formed in the 1980s among Arab fighters in Afghanistan, in the war against the Soviet army. After that war it turned to attacking Western countries. Its best-known leader was Osama bin Laden. The attack most students have heard of is 11 September 2001 in the United States: hijacked planes hit the World Trade Center in New York and brought it down; another hit the Pentagon; a fourth plane crashed. Thousands of people died. Governments then spent years hunting the group. The Arabic name means “the base” or “the foundation.” Though actually people sometimes stick the name on any Islamist attack they see on the news; that is loose and often wrong. Spellings in English wander (al-Qaeda, al-Qaida); the group is the same.