Everyone has been exposed to film to some degree but how many have a knowledge of the history and milestones of this commanding medium? If younger people are introduced to literature, music, fine arts, dance and other forms, then why should film be ignored?
A word to more mature individuals seeking to introduce younger ones to film: seek pictures which still have a pulse, a life force which shows a connection to life as it is still known, despite differences in fads and fashions. Don't expect younger people to love something simply because it was popular in your youth, you loved it, or it conjures sentimental memories of another era.
For younger viewers searching on their own: try and find films which speak to you in some way and, not that you probably won't anyway, don't trust established views telling you what you should and shouldn't think is good, including this by no means definitive nor complete list.
