An intranet is a private network that is contained within a business. It can be made up of local area networks - LANs or through wide area networks - WANs. An intranet will typically be connected to the outside world via a gateway computer.

The key reason to have an Intranet is to share company information and resources. Intranets can also be used for teleconferencing.

An intranet uses TCP/IP, Hypertext Transfer Protocol, and other Internet protocols and in general looks like a private version of the Internet. Companies can use tunneling to send private encrypted information over public networks.

An Intranet will usually allow users to connect to it from outside via a firewall which can maintain the security of the the organisation. When part of the Intranet is made accessible to outside user it is called an extranet.