An intranet is a private enterprise network.

User TypesAny user having dial up of Internet access lineOrganization employees and Internal company departments
UsageAccess all kind of informationInternal employee communication
SecurityLow security. Configured under O security level in firewallHigh security. Configured under 100 security level in firewall
Regulated byInternet Architecture Board (IAB)It is regulated by an organization
Coverage Wide AreaWithin an organization
Access Large number of users Limited number of users
System failure UnpredictableSystem availability is high since system is monitored by authority
Snippet from Wikipedia: Intranet

An intranet is a computer network for sharing information, collaboration tools, operational systems, and other computing services within an organization, usually to the exclusion of access by outsiders. The term is used in contrast to public networks, such as the Internet, but uses most of the same technology based on the Internet Protocol Suite.

A company-wide intranet can constitute an important focal point of internal communication and collaboration, and provide a single starting point to access internal and external resources. In its simplest form, an intranet is established with the technologies for local area networks (LANs) and wide area networks (WANs). Many modern intranets have search engines, user profiles, blogs, mobile apps with notifications, and events planning within their infrastructure.

An intranet is sometimes contrasted to an extranet. While an intranet is generally restricted to employees of the organization, extranets may also be accessed by customers, suppliers, or other approved parties. Extranets extend a private network onto the Internet with special provisions for authentication, authorization and accounting (AAA protocol).