DotNetNuke® (DNN) is an Open Source Framework ideal for creating Web Applications. That's right... Web Applications, not websites.
What's the difference?
Websites are largely static collections of text and images displayed as pages in a browser. Making changes is time consuming as each page has to be edited individually and can be quite expensive as most firms charge by the hour. They also determine the cost of your site development based on the number of pages required. In other words, you pay for all the inefficiencies.
Web Applications are based on a Web Application Framework that provides all the tools necessary to develop, render and maintain an exciting and dynamic web presence. The end user can modify the content and/or look and feel of the site at any time from anywhere on the planet with nothing more than an Internet connection and a browser.
DotNetNuke® is a versatile, open source (i.e. it's free), user-friendly, feature rich framework, which is based on Microsoft's .NET technology. Skins (the look and feel) can be purchased online or created by skilled designers and easily applied to change the entire appearance of the site in seconds. Many modules, which provide the display mechanism for the content of the site, are included with DNN, but custom modules can be purchased online or coded to spec by talented software developers.
The end result is a compelling, dynamic, inexpensive, easily maintained "website" that will set you apart from the competition.