"New research from NM Incite, a Nielsen McKinsey company, reveals that there are innumerable factors that help Facebook users decide to add a friend or cull someone from the fold, though knowing someone in real life is the top reason cited for friend-ing someone (82%) and offensive comments are the main reason someone gets the boot (55%).While some Internet interactions are online-only relationships, the most common reason we add friends on Facebook is because we know people in real life."
So why do you friend someone? I have two Facebook accounts- one for "friends and family" and one for "Friends and work." For work, I'll friend almost anyone in the library field and authors. I seldom de-friend people but I will "silence" them if they post too often or rare playing too many games. I love hearing people's ideas and will follow quite a few links if they sound interesting. What about you?