Isn't Facebook more of a paradoxical phenomenon? You go to Facebook to use Facebook to communicate with people on Facebook. My point being that it's both a community and a medium of communication at the same time?

You go on Hacker News to use hacker news to communicate with other users of Hacker News.

This also works for every other website in existence, I think.

Hacker news is somewhat more of a community though, because it's a group based on common interests.

Facebook is supposed to be for everyone, so it's not really a group at all.