What are the core classes In C#? [closed]

Question

Which class hierarchy is most necessary in order to get an excellent grasp of C#, for the aspiring C# desktop applications programmer? Not just the totally obvious stuff.

EDIT: To clarify, I mean, that as I am learning C#, I would like to know what are the classes I should be acquainted with, which aren't necessarily going to be obvious to someone who isn't experienced enough to know what is, and is not important to learn.

EDIT2: Are there any more obscure classes? So far I know a good deal about many of these already given.

Answer 1

System.Collections

System.Data (many apps have a database backend)

System.Windows (as it's a desktop app)

System.Graphics (as above)

System.Diagnostics (provides various objects and methods useful for logging and when debugging, always important in commercial code).

These namespaces contain important classes to do a lot of everyday stuff done in most applications, regardless of whether the app is web or desktop based. Windows is pretty much just for desktop apps (like you said you do), and graphics will compliment that closely (also compliments web apps too). You'd do well to learn all the classes in these namespaces, even though you asked for just classes.

Answer 2

Just found this link in another thread: map

Also, download Reflector and browse through the .NET Framework classes, starting with mscorlib.dll and System.dll.