Facebook, created by a 19-year-old Harvard student in 2004, has grown into a social networking site with some 60 million members, comparable to the whole population of Britain. The author provides ten things you should know about Facebook. 1: Its total membership is about a fifth of rival MySpace, but active users are doubling every six months. 2: Facebook contents can range as widely as the interests of its members, the site's search function helping members find others with shared interests. 3: People use Facebook as a social icebreaker, as a handy place to upload photos or other personal content, or to have a handy personal spot on the Web. 4: Facebook provides a software development kit (SDK) allowing users and developers to create applications to enhance and extend the Facebook experience. 5: Facebook is an effective advertising and promotional tool, more flexible than MySpace. 6: Facebook is not just for college students any more--more than half the users are no longer in college, and users 25 and over are the fastest growing demographic. 7: Facebook members can form groups, of which there are now a vast number running the gambit from political groups to avowedly pointless groups such as The Largest Facebook Group Ever. 8: Uploading photos is easy, making Facebook the most popular photo sharing site online. 9: A search feature makes it easy to find your existing friends or search for old acquaintances. 10: Facebook supplies easy-to-use privacy controls for setting up personal sites.