Comparison Between Internet, Intranet & Extranet

The Internet is a network that is available to anyone with an Internet-connected device. It is a massive collection of networks sharing information publicly in the form of interlinked Web pages. Internet Protocol defines a site's unique location which most users see as a domain name or URL. The network is literally world-wide and is often referred to as the world wide web.

An intranet network is only available to a small group of people. Intranets are mainly used within businesses and organizations to provide access to files and applications among networked computers and servers. Intranets may or may not have access to the Internet. If an intranet does connect to the Internet, a firewall is used to prevent outside access to the intranet. The purpose is to allow people within the same company to share information over a local area network. It is sometimes referred to as a private Internet.

An extranet is similar to an intranet, but is accessible via a Web portal. An extranet may be accessed from anywhere if the user has a valid user name and password. The purpose of this type of network is to allow collaboration and sharing of resources not only in-house but with a select group of outside users. For instance, businesses will use an extranet to allow customers to log in to provide input on projects. Another example is using a virtual private network to allow employees to log in to the network when they're are not in the office.

The main difference between the three is accessibility. The Internet is public while the other two are highly restricted. Home users, if they use one at all, would only use an intranet to share files between computers and typically use the Internet when searching for and sharing information. Businesses and organizations are the main users of both intranets and extranets in order to restrict access to confidential data.