Largely used as a US bogeyman when the US wants to justify it's Imperialist actions globally. Al Qaeda is a loosely affiliated group based on a shared belief system, kind of like these white supremacist Timothy McVeigh guys in the US. They share a common vision, but are not organized.
In reality the vision of Al Qaeda is more reasonable than the McVeigh types, because they have concrete facts to back up thier fanaticism, such as the US DOES have military based in Saudi Arabia and in Arab lands where they broke treaties and lied to maintain them there, and the Saudi family (AL Qaeda's true enemy) is ignoring them wishes of the masses of Arabs who want them removed. Thus 9-11... its simple to understand if you care to look at the facts.
99.9% of Americans ignore the facts which is why they have GW Bush as a president, he is them...
HE IS THEM, same outlook on the world, an ignorant, blind, dry drunk view.
Compared to Pakistan, Al Qaeda is a speck of sand on the beach.