Testing and debugging your application is a vital part of any development cycle. Because all but the very smallest of development projects is nearly certain to have mistakes in the first draft, finding and correcting those issues is important for the overall integrity of your work. In this chapter, you learn about techniques and technologies for debugging WPF applications. You learn how to use user interface (UI) automation to test the user interface and the WPF Tree Visualizer to explore the properties of the WPF visual tree. You learn how to use PresentationTraceSources to view trace information associated with WPF applications and to use Intellitrace to view highly selected trace data.