Facebook has become a worldwide phenomenon, with over 500 million people signing up for the service. A large proportion of populations in western countries, like the UK, are signed up.

The site was founded by Mark Zuckerberg, Chris Hughes, Dustin Moskovitz and Eduardo Saverin. Mark Zuckerberg is often considered the sole founder of the site, due to him being the public face of the company, and currently owning 24% of the stock.

To begin with, Facebook was only accessible to college students at Harvard university. It was soon expanded to students of local universities. And finally to the general public.

The site is classified as social networking. It was not the first social networking website, but it has gone on to be the most successful (as of 2010).

While the Internet has largely supported anonymous posting and privacy. Facebook was at odds with that philosophy. Instead, Facebook users only have the option of signing up with their real world details and persona.

Facebook has been noted for the accessibility of contacting old friends, estranged family members or general acquaintances. The simple interface can be accessed by mobile phone, and is easily operated by technological novices. The planning of social events and news is also revolutionized.

Some critics have questioned the long term effects of using the service. Information posted in one's youth may be regretted in adulthood. The ability to reinvent oneself is also hampered by the past being so easily accessible.

Therefore, it is fair to say that privacy will most likely be the main bone of contention as Facebook evolves. What Facebook will do with it's information, it's attempt to monetize it's service, will no doubt lead to much publicity in the upcoming years.

To date, Facebook has a simple interface. A profile, a wall (where users can post any topic they like about themselves or the world in general), a friends list, and a photo album. Currently users can edit privacy settings so that their wall and parts of their profile can be hidden. User's friend list remains open to view.