What is ASP.NET?

ASP.NET is an inherent part of the .NET-framework. It enables the object-oriented construction and programming of big web-applications which can be used via browser without any further installations and independently from time and place.

ASP.NET can be used to set up Internet-sites as well as very complex Intranet- or Extranet-projects. One example for such an application is the Content Management System QualiSite which is 100% ASP.NET and therefore based on .NET. The  website you are actually surfing has been built with QualiSite, for example.