An intranet site is a web site that is viewable only to those within an organization’s network.
An intranet is protected from the outside world either by not being connected to the outside or through a series of hardware and software obstacles known as a firewall (a security system with specialized software to prevent outsiders from entering private networks).
An intranet may be as simple as two computers networked in a home office, or as complex as a network linking the offices of a global corporation.
The reasons for having an intranet are to communicate among the members of the organization and to involve them in improving their effectiveness and collaboration.