LinkedIn is a business-related 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, Spanish, Romanian, Russian and Turkish. Quantcast reports Linkedin has 21.4 million monthly unique U.S. visitors and 47.6 million globally. In June 2011, LinkedIn has 33.9 million unique visitors, up 63 percent from a year earlier and surpassed MySpace.
One purpose of the site is to allow registered users to maintain a list of contact details of people with whom they have some level of relationship, called Connections. Users can invite anyone (whether a site user or not) to become a connection. However, if the recipient of an invitation selects "I don't know", this counts against the person inviting them, and after five such "IDKs" a member cannot invite another to connect without first supplying their recipient mail address.
This list of connections can then be used in a number of ways:
A contact network is built up consisting of their direct connections, the connections of each of their connections and also the connections of second-degree connections. This can be used to gain an introduction to someone a person wishes to know through a mutual contact.
It can then be used to find jobs, people and business opportunities recommended by someone in one's contact network.
Employers can list jobs and search for potential candidates.
Job seekers can review the profile of hiring managers and discover which of their existing contacts can introduce them.
Users can post their own photos and view photos of others to aid in identification.
Users can now follow different companies and can get notification about the new joining and offers available.
Users can save jobs which they would like to apply for.