In Back to the Future, Marty McFly first travels to 1955.
Marty begins in 1985, then accidentally activates Doc Brown’s DeLorean time machine while fleeing armed Libyan terrorists. Because the time machine’s destination display is set to November 5, 1955—the day Doc conceived the flux capacitor—Marty is sent thirty years into the past.
His arrival creates the film’s central problem. Marty encounters his teenage parents before they have fallen in love, and his interference threatens to erase his own future existence. He must persuade the shy George McFly to stand up to Biff Tannen and ensure that George and Lorraine become a couple.
The other dates are connected with later adventures. Marty visits 1985 again when he returns home, travels to 2015 in Back to the Future Part II, and goes to 1885 in Back to the Future Part III to rescue Doc Brown. The famous number 88 is the DeLorean’s required speed in miles per hour, while 1955 is the first major destination in Marty’s time-travel story.