A fandom is a group of people who share a common interest. So as an example, if I create a public fandom that contains feeds about animals, it will naturally be added by people who like or are interested in animals. Thus, the Animals Fandom has been created. (If you keep the fandom private, it just means you are the only one in that particular fandom.)
There was a lot of struggle to come up with the right name. First, we called them “playlists” (which captured the idea that they arrange content by topic/interest); then we called them “groups” (which captures the idea that they are groups of people sharing comments with each other). Finally, we settled on “Fandom,” which I think is a unique word that captures both the concepts of (1) a community of similarly interested people, and (2) a collection of items and feeds related to that interest.
Alas, it still isn’t perfect because “Fandom” doesn’t naturally capture the idea of a private playlist that a user collects, just for themselves–which is a perfectly fine way to use the Fandom function. So we need to stretch the term a little bit, to encompass the notation that a person can have “their own personal Fandom”–which they can keep private, or may choose to share with others later.
All in all, I think “Fandom” is the right word, and don’t see us changing it . . . though we are always open to suggestions. 