LinkedIn is a business-oriented social networking site. Founded in December 2002 and launched in May 2003, it is mainly used for professional networking. As of 22 March 2011, LinkedIn reports more than 100 million registered users, spanning more than 200 countries and territories worldwide. The site is available in English, French, German, Italian, Portuguese and Spanish. Quantcast reports Linkedin has 21.4 million monthly unique U.S. visitors and 47.6 million globally.