The War on Terror: What caused it and how did it start?

I have been in shock (literally) since President Obama announced on TV a week ago that Osama bin Laden had been killed.  It has been 10 years since 9/11 and I have forgotten a lot of the details about what caused Osama to attack America and our subsequent War on Terror.  I had to look it up on the Internet and I found this explanation for the attack on America on Wiki Answers:

…. is it surprising that Bin Laden started a 10 year terror campaign to get US troops out of Saudi Arabia as a result of Saudi dissidents being tortured for opposing the presence of US troops in Saudi Arabia following the carnage of the gulf war in which the US government was accused of not only massacring fleeing Iraqi soldiers from Kuwait but also air strikes that collaterally killed Iraqi children and babies in the gulf war where US bombs killed 200,000 Iraqis, destroyed 20,000 Iraqi homes, leveled schools and hospitals.