A way to communicate with people either by words or by photos. It makes it way easier than emailing people or calling people. I also use FB to receive updates and photos from “liked” locations – stores, fairs, museums, magazines, newspapers, political organizations. These can then be shared with my friends or groups if I want to.
The best thing that FB has done for me is put me in touch with people that, in the pre-email and Facebook days, were lost forever. Friends from when I was little, teachers, babysitters, etc.