Intranet

No, it's not 'Internet' misspelt, but a network which provides similar services within an organisation to those provided by the Internet outside it but which is not necessarily connected to the Internet. Where an Intranet is made available to the Internet in a restricted manner (for example, for customers or staff working outside the office), it is referred to as an Extranet. A firewall is usually employed to protect an Intranet from unwanted access attempts.

See also:
[Extranet]  [Firewall]