LinkedIn

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:

• A contact network is built up consisting of their direct connections, the connections of each of their connections (termed second-degree connections) and also the connections of second-degree connections (termed third-degree connections). This can be used to gain an introduction to someone you wish to know through a mutual, trusted 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.

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.^[7]

The feature LinkedIn Answers,^[8] similar to Google Answers ^[9] or 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,^[10] 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.

From: http://en.wikipedia.org/wiki/LinkedIn