Intranet is a private network that belongs to a particular organization. It is designed for the exclusive use of an organization and its associates such as employees, customers and other authorized people. So, it is like a private internet that is operating within an organization.
It is based on the internet protocols (TCP/IP) and is protected from unauthorized access with firewalls and other security systems. So, users on the intranet can access the internet but the internet users can't access the intranet if they are not authorized for it.
Some of the benefits of intranet are: