Sams Teach Yourself ASP.NET in 21 Days, Second Edition By Chris Payne
Table of Contents
Day 2. Building ASP.NET Pages
You may be confused by this section and ask, "Aren't I learning a new programming language already?" ASP.NET is not a programming language. It's simply a framework that allows you to build applications over the Web.
Having said that, you can write your ASP.NET pages in just about any programming language you want such as Visual Basic.NET or C# or JScript.NET. All of the code is compiled to MSIL anyway, and the compilers must emit metadata describing each application. Because of this intermediate compiler language, the JIT compiler only needs to understand MSIL. Days 3 and 4 will examine VB.NET and C#, the two most common languages for ASP.NET programming.
Because the CLR needs to ensure that all of its parts can work together, it defines a basic subset of features that every programming language must follow. Otherwise, objects developed in different languages wouldn't work together properly. This subset is called the Common Language Specification (CLS). As long as your applications only use features that are available in the CLS, they're guaranteed to work on all platforms and will be completely usable by objects compiled in other languages.