C# Applications
Windows applications:
This is made simple by using the Windows Forms module of the .NET Framework, which is a library of controls (such as buttons, toolbars, menus, and so on) that you can use to build a Windows user interface (UI).
Web applications:
These are Web pages such as might be viewed through any Web browser. The .NET Framework includes a powerful system for generating Web content dynamically, allowing personalization, security, and much more. This system is called ASP.NET (Active Server Pages .NET), and you can use C# to create ASP.NET applications using Web Forms.
Web services:
These are a new and exciting way to create versatile distributed applications. Using Web services you can exchange virtually any data over the Internet, using the same simple syntax regardless of the language used to create a Web service or the system that it resides on.