Glossary:
Intranet
An Intranet is a private computer network that uses the same technology as the Internet to share information. Typically it will be a TCP/IP network with web servers, email and FTP.
The two main ways it differs from the Internet is firstly that it is smaller in coverage (usually not global) and secondly it is restricted to a specific group of people. Usually it is intended for members or employees of the organisation who runs the Intranet.