What is an Intranet?

In the broadest sense of the word an intranet is a network of computers that communicate using Internet protocols, but are not part of World Wide Web. Usually an intranet is considered to be the internal computer network of an organization, but like many things, the intranet concept is a little more complicated than that.

"The intranet is a resource and communications platform for the organization it is part of."

It is also common to refer to the intranet as the specific web sites or applications that can be found on the network, not the network itself. Many organizations create a central portal on the network where a variety of company resources can be located through a web browser. These intranet resources can include all sorts of functionality: Common forms for the organization, reference material, customer relationship management systems, calendars, company news, contact databases, discussion forums, knowledge management utilities, and other applications. While this doesn't make the definition of the word intranet any clearer, it does make the intranet's usage more obvious: the intranet is a resource and communications platform for the organization it is part of.

Intranet, Extranet, and Internet

One of the key differences between the Internet and an intranet is that the intranet is not intended to be publicly available. On the contrary, many intranets are hidden behind multiple firewalls to protect sensitive company data from the prying eyes of the world. It would be easy to think that the intranet is simply internal to the organization's physical location, however this is not always the case, many companies open up their intranets to remote access via modem dial-in.

The matter of extranets complicates the matter further. An extranet holds a position somewhere between the Internet and an intranet. Extranets occur when limited intranet access is expanded to users external to the organization, usually a company's business clients. They are usually run on the company's internal network in order to make company resources available to users, but use the Internet for transport since the users are external to the organization's network. Again, the key is that the extranet is a closed resource for a specific group of users, and is not intended for public consumption. There is little point in debating whether any web site with a closed member area is an extranet or not, the definitions are not that exact. We'll discuss extranets further in Chapter 14.

Taking the above into account, another way of looking at the Internet, intranet, and extranets would be to say that the only difference between the three is the permissions you set on the resources.