|Type of site||Professional network service|
Mountain View, CA, USA
|Revenue||$17 million (December 31, 2008 Fiscal Year)|
LinkedIn (pronounced /ˈlɪŋkt.ˈɪn/) 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 11 February 2010 , LinkedIn had more than 60 million registered users, spanning more than 200 countries and territories worldwide.
Founder Reid Hoffman, previously CEO of LinkedIn and now executive vice president of PayPal, oversees day-to-day operations and is also Chairman of the Board. Dipchand Nishar is Vice President of Products. LinkedIn is headquartered in Mountain View, California, with offices in Omaha, Chicago, New York and London. They are funded by Greylock, Sequoia Capital, Bessemer Venture Partners and the European Founders Fund. LinkedIn reached profitability in March 2006.
On June 17, 2008, Sequoia Capital, Greylock Partners, and other venture capital firms purchased a 5% stake in the company for $53 million, giving the company a post-money valuation of approximately $1 billion.
LinkedIn has more than 60 million users worldwide, of which approximately half are in the United States. 11 million are from Europe. With 3 million users, India is the fastest-growing country as of 2009. The Netherlands has the highest adoption rate per capita at 30%.
The purpose of the site is to allow registered users to maintain a list of contact details of people they know and trust in business. The people in the list are called Connections. Users can invite anyone (whether a site user or not) to become a connection.
This list of connections can then be used in a number of ways:
The "gated-access approach" (where contact with any professional requires either a preexisting relationship, or the intervention of a contact of theirs) is intended to build trust among the service's users. LinkedIn participates in EU's International Safe Harbor Privacy Principles.
LinkedIn also allows users to research companies with which they may be interested in working. When typing the name of a given company in the search box, statistics about the company are provided. These may include the ratio of female to male employees, the percentage of the most common titles/positions held within the company, the location of the company's headquarters and offices, or a list of present, past, and former employees.
The feature LinkedIn Answers, similar to Yahoo! Answers, allows users to ask questions for the community to answer. This feature is free and the main differences from the latter two services are that questions are potentially more business-oriented, and the identity of the people asking and answering questions is known.
The searchable LinkedIn Groups, feature allows users to establish new business relationships by joining alumni, industry, or professional and other relevant groups. LinkedIn groups can be created in any subjects and by any member of LinkedIn. Some groups are specialized groups dealing with a narrow domain or industry whereas others are very broad and generic in nature. These groups add an unique element to the networking site in that it provides connections on a more personal basis. Professionals are more likely to want to connect with you online if they are somehow connected with you in life. These groups may include: alumni associations, greek affiliations, professional societies, sports team connections, etc. These groups also allow for professionals to post job openings or answer questions concerning a professional hardship. The connections made through LinkedIn Groups may be more beneficial than an unknown connection.
The newest LinkedIn feature is LinkedIn Polls, still in alpha.
A mobile version of the site was launched in February 2008 which gives access to a reduced feature set over a mobile phone. The mobile service is available in six languages: Chinese, English, French, German, Japanese and Spanish. 
In mid-2008, LinkedIn launched LinkedIn DirectAds as a form of sponsored advertising.
In October, 2008, LinkedIn revealed plans to opening its social network of 30 million professionals globally as a potential sample for business-to-business research. And, in doing so it's testing a potential social-network revenue model-research that to some appears more promising than advertising. 
In October, 2008, LinkedIn enabled an "applications platform" that allows other online services to be embedded within a member's profile page. For example, among the initial applications were an Amazon Reading List that allows LinkedIn members to display books they are reading and a Six Apart, WordPress and TypePad application that allows members to display their latest blog postings within their LinkedIn profile.
The Search, Network, and Analytics team at LinkedIn has a web site that hosts the open source projects built by the group. The most notable one is Project Voldemort, a distributed key-value structured storage system with low-latency similar in purpose to Amazon's Dynamo and Google's BigTable.