LinkedIn (NYSE: LNKD) (play /ˌlɪŋkt.ˈɪn/) is a social networking website for people in professional occupations. Founded in December 2002 and launched on May 5, 2003, it is mainly used for professional networking. As of June 2012, LinkedIn reports more than 175 million registered users in more than 200 countries and territories.
Quantcast reports LinkedIn has 21.4 million monthly unique U.S. visitors and 47.6 million globally. In June 2011, LinkedIn had 33.9 million unique visitors, up 63 percent from a year earlier and surpassing MySpace. LinkedIn filed for an initial public offering in January 2011 and traded its first shares on May 19, 2011, under the NYSE symbol "LNKD". [Source: Wikipedia]