Data binding is one of the fundamental concepts used for good Windows Phone application design, but can be difficult to grasp for newcomers. The core concept is this: No one wants to manually update the user interface elements. It’s best to have the UI automatically reflect the state of the application. Data binding helps us do this. We can work exclusively on our Windows Phone UI, bind the values in the UI and then work on the inner logic of the application knowing that all the updates are being reflected to the user. Because of the power in the model, as you see in this video, there are some really great “fringe” benefits in terms of interaction and design that we get, along with the core benefits. For more information, see Data binding for Windows Phone.