what is windows in Winfforms??

Namespaces in C# can be nested. Nesting can be done like this:

namespace A

{

   namespace B

   {

   }

} 

or, for brevity, like this:

namespace A.B

{

}

So System is a namespace in the .NET framework and so too is System.Windows.Forms.

Console is a class in the System namespace and Form, Control, Button. TextBox, ListBox etc are classes in the System.Windows.Forms namespace.

Check this link for more detail on namespaces:

http://www.csharp-station.com/tutorials/lesson06.aspx