These are web-based networks of internet users with common interests or issues. They make it easy for members of the same community to contact each other and exchange news, videos, photos and so on. Examples are MySpace, Viadeo, LinkedIn, Ziki, Facebook, Asmallworld, etc. Over half of all internet users are said to have visited a social networking site in 2009. Registering with these networks is usually free, though they charge for some of the services they offer.