Who?
Who was Osama bin Laden? A son of a wealthy Saudi businessman, bin Laden was a devout Muslim who created the secretive al-Qaeda ('the base') terror organisation. The US says bin Laden was the mastermind behind several mass-casualty acts of terror, including the attacks on September 11, 2001, in New York and Washington.
What?
What was bin Laden's ideology? He believed in a very strict form of Islam, which advocates holy war, or jihad, to create an ideal world based on Islamic sharia law. He saw the US and Israel as the two main causes of global injustice against Muslims. Bin Laden believed that it was the duty of every good Muslim to fight and kill Americans and Jews, and their Muslim allies, including civilians.
When?
When was al-Qaeda formed? In the 1980s, bin Laden joined the thousands of foreign Muslim fighters in Afghanistan waging war against the Soviet Union's army, which had invaded the country. In August 1988, the rich Saudi set up his own close-knit group of fighters to launch a terror campaign against the US. He had come to see the US as an enemy of Islam because it supported corrupt Arab leaders, including Saudi Arabia's royal family.