The 9/11 truth movement encompasses a disparate group of adherents to a set of overlapping conspiracy theories that dispute the general consensus of the September 11 attacks that a group of Al-Qaeda terrorists had hijacked four airliners and crashed them into the Pentagon and the original World Trade Center Twin Towers, which consequently collapsed. The primary focus is what the movement perceives as missed information that they allege is not adequately explained in the official National Institute of Standards and Technology (NIST) reports, such as the collapse of 7 World Trade Center. They believe in a cover-up and, at the least, complicity by insiders.