Once upon a time, a friend was someone you knew, someone you hung out with, someone to share fun times with and sometimes more. Now, thanks to social-networking, the term "friend" has become harder to define...
Best Friend Forever (BFF) - Your closest friend - someone you share your secrets with, do things together and may even give gifts or money. The "forever" part isn't guaranteed, though.
Best Friend (BF) - Sort of like the above, but you don't share as much and it's a bit more of a loose relationship.
Friend - Someone you regularly hang out with or talk with, and like.
Frenemy - Someone you regularly hang out with or talk with, but you sometimes dislike them, they sometimes dislike you, or both.
Facebook Friend - Someone you share things with on Facebook. Could also be any or none of the above.
"Friend" on Most Other Websites - Might mean that you track each other's updates or profiles. This could easily be someone that have never had any direct contact with, even on a message board. Or, it could be any of the above.
Agent0042: Oh yeah, I have over 80 "friends" on TV.com. Some of these names I don't even recognize.