I can't even begin to list all the advantages of ASP.NET over traditional ASP. In a nutshell, traditional ASP was a good idea that didn't scale that well at all. The programming was all done in very error prone scripting in an environment that offered very little in the way of extensibility and other requirements for large development projects. The greatest flaw with traditional ASP, in my opinion, is that the debugging support is so amazingly poor that most developers cannot easily solve development problems.
ASP.NET moves us into the world of a real Application Programming Interface (API) on top of Web applications. With real development, your code is compiled and syntax checked before the user ever connects. The compilation speeds up your application tremendously. Additionally, ASP.NET breaks apart the Web UI from the actual code so it's much easier to manage. You can also debug ASP.NET applications extremely easily with one of the most powerful debuggers ever made. Click here for more information about the advantages of ASP.NET.
This was first published in February 2003