how many parts to back to the future
Back to the Future Back to the Future's success led to two film sequels: Back to the Future Part II and Back to the Future Part III.
Back to the Future Part II On October 26, 1985, Dr. Emmett Brown arrives in the DeLorean time machine and persuades Marty McFly and his girlfriend, Jennifer Parker, to travel to the future with him, and help their future children. Biff Tannen witnesses their departure. They arrive on October 21, 2015, where Doc electronically knocks out Jennifer, and leaves her asleep in an alley, explaining that she should not have too much knowledge of future events. He has Marty pose as his own son and lookalike Marty Jr. to refuse an offer to participate in a robbery with Biff's grandson Griff, thus saving both of Marty's children from prison.