This is the fifth video in a series that will take you step-by-step on building a Prism application that mimics Microsoft Outlook. In this video, we implemented our navigation using the Prism navigation APIs as well as some navigation objects we created to provide our navigation path. We talked a little about INavigationAware interface, IConfirmNavigationRequest interface, and how the View and ViewModel can participate in the Prism navigation process. DelegateCommand and CompositeCommand were also discussed. We also implemented our own little MVVM framework which is made up of only two interfaces, IViewBase and IViewModel. You saw the first glimpse of the EventAggregator and much more. Wow, we really covered a lot in this video. Of course we only had time to implement this functionality in the Silverlight version of the application. So, I went ahead and implemented the same functionality in the WPF version as well. I hope you enjoy the video and be sure to ask any questions or request to see any features in the comments section.