Windows Forms (WinForms) is a UI framework for building Windows desktop applications. It is a .NET wrapper over Windows user interface libraries, such as User32 and GDI+. It also offers controls and other functionality that is unique to Windows Forms.
Windows Forms also provides one of the most productive ways to create desktop applications based on the visual designer provided in Visual Studio. It enables drag-and-drop of visual controls and other similar functionality that make it easy to build desktop applications.