System.Windows.Forms namespace in .NET Framework Class Library
The System.Windows.Forms namespace contains classes for creating Windows-based applications that take full advantage of the rich user interface features available in the Microsoft Windows operating system.
Most classes within the System.Windows.Forms namespace derive from the Control class. The Control class provides the base functionality for all controls that are displayed on a Form. The Form class represents a window within an application. This includes dialog boxes, modeless windows, and Multiple Document Interface (MDI) client and parent windows. You can also create your own controls by deriving from the UserControl class.