User Controls are commonly used in ASP.NET web sites. Their main idea is to bundle a set of controls (buttons, text fields, textareas, etc) and form a new and more complex control. That could be useful in the case that we want to use the same set of controls and functionality across a number of pages in a site.

This tutorial will demonstrate how we can make use of User Controls in WinForm applications to create a Multiple Document Interface (MDI in short).