I was checking to know what is the .NET framework exactly. I understand that ASP.NET is just built over the .NET and that it uses all the web-technologies-services of .NET. So to do this I believe that they must use the same underlying Class Library as of the .NET to build ASP.NET technology.

Short answer: Yes.

Longer answer: Yes, but there are tons of capabilities added specifically for the support of the ASP.NET environment that are not intrinsically part of the .NET framework.

Just for starters, consider the incremental code compilation that is done in serving up an ASP.NET page. That's completely outside the scope of the basic .NET framework.

But yet it is, indeed, built on top of the .NET framework. Without the framework, none of it could be done.

And then, too, there are all the ASP.NET controls. Controls designed to produce HTML output and interact with HTML and JavaScript. Again, none of that capability is part of the base .NET framework. And while you don't HAVE to build such capability on top of the .NET framework (well, after all, JSP and JSEE are all built on top of a Java framework...yet they accomplish the same kinds of things) clearly the ASP.NET controls are built in that way.

So... Where's the line? I dunno about you, but I don't worry about it. I just treat the .NET framework as if it is an integral part of ASP.NET and it all works right for me.