Originally developed by Harvard student Mark Zuckerberg and designed so that students on campus could stay in touch. Today it's developed into the UK's most popular social networking site and the most popular website in the world for uploading photos.

Facebook shares many of the same issues as MySpace but benefits from barring users from viewing your account unless they are an approved member of your friends list. Additionally there have been concerns expressed regarding the use of Facebook as a means of surveillance and data mining.

200 million