First, what are Twitter and Facebook? Twitter is a real-time network that allows users to share ("tweet") whatever they're interested in, using 140 characters or fewer. On Twitter, you "follow" people, businesses or organizations that you're interested in, and you build a following for yourself. You can upload pictures, share links and videos in your "tweet."
Facebook is also a social networking site. On Facebook, users create a profile and add other users as friends. On Facebook, you can communicate with others about your "status" through your profile page, send personal messages or private chat. You can join interest groups, invite others to events, and share photos, links and videos.
Both Twitter and Facebook allow you to stay tuned via your mobile devices. Which means you can "tweet" or update your "status" anytime, anywhere.