Intranet

Intranet 
         is the generic term for a collection of private computer networks within an organization. An intranet uses network technologies as a tool to facilitate communication between people or work groups to improve the data sharing capability and overall knowledge base of an organization's employees.

Intranets utilize standard network hardware and software technologies like Ethernet, WiFi, TCP/IP, Web browsers and Web servers. An organization's intranet typically includes Internet access but is firewalled so that its computers cannot be reached directly from the outside.

A common extension to intranets, called extranets, opens this firewall to provide controlled access to outsiders.

Many schools and non-profit groups have deployed them, but an intranet is still seen primarily as a corporate productivity tool. A simple intranet consists of an internal email system and perhaps a message board service. More sophisticated intranets include Web sites and databases containing company news, forms, and personnel information. Besides email and groupware applications, an intranet generally incorporates internal Web sites, documents, and/or databases.

The business value of intranet solutions is generally accepted in larger corporations, but their worth has proven very difficult to quantify in terms of time saved or return on investment.

http://compnetworking.about.com/cs/intranets/g/bldef_intranet.htm