ASP.NET is a set of web application development technologies marketed by Microsoft. <br><br>Microsoft has completely rebuilt ASP.NET, based on the Common Language Runtime (CLR) shared by all Microsoft .NET applications. <br><br>Programmers can write ASP.NET code using any of the different programming languages supported by the .NET Framework, usually C#, Visual Basic.NET, or JScript .NET, but also including open-source languages such as Perl and Python.