MDI Applications (Multiple-Document Interface)

A C# Windows application usually allows only a single Form to be opened at any given point in time, this works fine for smaller applications, but when we need to develop larger applications, we need a comprehensive menu structure to navigate through the various forms, this is where the MDI Applications help us.

Multiple-Document Interface (MDI) application, are those which have a MDI parent form, this form will be the parent of all the other forms in the Application, typically this form will contain the Menu which is used to navigate to the other forms in the application. 

A form in an MDI application is set as the MDI Parent by setting the IsMDIContainer property to true. Once this property is set to true, this form will act as the Parent form for the application. We can add Menu control to this form.