ASP.NET is a web application framework developed and marketed by Microsoft which allow programmers to build enterprise-class dynamic web sites, web applications and web services with minimum coding. ASP.NET is part of the .NET Framework, and ASP.NET applications are coded by accessing classes in the .NET Framework.
ASP.NET is the successor to Microsoft’s Active Server Pages (ASP) technology. It was first released in January 2002 with version 1.0 of the .NET Framework.
ASP.NET 4.0 is built on the Common Language Runtime (CLR), allowing programmers to write ASP.NET 4.0 code using any supported .NET language. You can code your applications in any language compatible with the common language runtime (CLR), including Microsoft Visual Basic and C#. These languages enable you to develop ASP.NET applications that benefit from the common language runtime, type safety, inheritance, and so on.