We have drawn on publicly available information from service providers' websites (particularly each service's Terms of Use and Privacy Policy), as well as trying out each of the sites reviewed extensively.

Additionally, we contacted the service providers included here and invited them to contribute to the project and comment on the chart entry for their service.

Where we have included specific terms that individual providers use for their site functionality or tools, we have made these in Facebook is a commercial social network site, whose head quarters are in California, USA.

This means that it is easy to use the site to store images to display elsewhere.

My Space is a commercial social network, owned by Fox Media.

All new profile pages are private by default and visible to friends only.

Members can also connect with their college or school network, which means that their profile becomes visible to other site members within that network.

The site features different profile tools for musicians and bands, giving them the ability to upload a limited amount of songs to their sites. Ning is a commercial company based California (USA), which offers members the ability to build their own public or private social network sites.

The ability to quickly tailor sites around particular topics has proven popular with educators despite concerns over adult-hosted Ning communities.

Facebook privacy and permissions settings are extensive.

Activity onsite centres on network and group pages, members profile pages, (that displays their activity and content), and the personalised Facebook home page which consists of a news feed of their friends activity, updates and notifications.

You Tube is the world's largest video sharing web site, and allows people around the world to upload, watch and share videos. It includes broadly popular music and entertainment content as well as political, sports, cultural, educational and other niche video.