There are many explanations about 9/11 including conspiracy theories, US involvement, Israeli involvement, Osama bin Laden (OBL) not being involved, oil region dominance, Vice President Dick Cheney as mastermind, etc. The list is long, and we may never have all the facts and know the intentions behind this tragic day.
What we do know is what will be recorded in the history books. OBL was angry at the US for abandoning the Afghanistani Mujahedeen after winning their struggle against the Soviet Union. OBL's anger was further deepened after Saudi Arabia used the US Military to rid Kuwait of invading Iraqis, forcing OBL to claim his primary US demand, for the US to remove themselves from all Muslim countries.
OBL wanted to send a strong message to the US, so he and Khalid Sheikh Mohammed (KSM) planned the World Trade Center attacks prompting a worldwide search for these perpetrators. KSM was captured in Rawalpindi, Pakistan on March 1, 2003 by the Pakistani intelligence services and is in US custody in Guantánamo Bay.
OBL was shot and killed inside a private residential compound in Abbottabad, Pakistan by US Navy SEALs and CIA operatives on May 2, 2011. It was a covert operation ordered by US President Barack Obama, and it ended with OBL buried at sea.
There are more details, but this is the simplified version that the next generation will read. Is it true? We may never know. We hope it's true, and that OBL was a lone individual who decided to take on a superpower in the name of his cause, whatever that may have been. And those who died 10 years ago were heroic because their deaths signified a cause. If it's not true, then those who died 10 years ago deserve much more because their deaths signified nothing.