A User Control is defined by means of a xaml file which consists of a visual tree of WPF Controls (e.g. starting with a Grid followed by Buttons, Lists, ….) and a code behind file. The program logic can be inside the code behind file or, following MVVM pattern, in a view model and a model.

In contrast to a Custom Control a User Control has no Control Template and thus cannot change its appearance. However, you can define dependency properties inside your code behind file to make the appearance adjustable.