I can't remember when I first saw Back to the Future but given I saw the third one at the cinema, I must have seen it when I was fairly young. There was just something about the idea of a time machine in the form of a DeLorean that captured the imagination, even if the film does come very much within the tradition of films in which the protagonist's interference results in a life that better suits what they want.
Marty McFly (Michael J Fox) starts the film in 1985 as an aspiring guitarist in high school. His father, George, is continually pushed around by his boss, Biff Tannen, and his siblings are equally lacklustre. Marty's friend, Doc Brown (Christopher Lloyd) invents a time machine, and Marty ends up back in 1955 where he encounters his high school aged parents. Doc Brown needs to get him back to 1985, but as they have no access to the plutonium on which the DeLorean runs, they have to wait until the night of the school dance, when Marty knows there will be a lightning storm, to generate the 1.21gigawatts the time machine needs. Will Marty get his parents together before he leaves?!
OK, so how can you not like Back to the Future?! Sure, all time travel films suffer from a central paradox, but unlike later films, in which the hero leaves something in the past/future for the next version of himself to find (see Deja Vu for a particularly nonsensical example), Marty is very much the first to time travel, and learns the hard way that you can't interfere in anything since actions in the past affect the present. OK, so it's a bit creepy that his teenaged mother gets a crush on him, and he has to engineer a meeting between her and his teenaged father - not many films flirt with incest in the 'boy meets girl' stakes, but somehow Back to the Future manages it without being icky.
Thing is, as cool as Michael J Fox makes Marty, and as awesome as Christopher Lloyd is as Doc Brown, it's actually Thomas F Wilson who steals the films for me as the various members of the Tannen family. My favourite incarnation is Buford 'Mad Dog' Tannen from Part III, but considering he plays three versions of Biff in Part I (bully Biff from 1985, then teenaged Biff from 1955, then meek and mild Biff back in new 1985), it just shows what one person can do with one character.
Back to the Future is one of those films I can watch again and again, and I love it just as much every time I watch it. Plus it has one of the best renditions of Johnny B. Goode that I've come across...