If I had to sum up the dependency properties in a single term, I would say that dependency properties are the regular property systems on steroids. The dependency properties really take what you know about properties to a whole new level, but that is also why it is one of the hardest concepts in Silverlight to grasp.

Most properties used on the UI objects in Silverlight use dependency properties. The most common place to write your own dependency properties is when writing your own control. The dependency properties are necessary when you wish to use data binding or styling, so if you think back about the projects we created in this book so far, you've used quite a lot of dependency properties but didn't even know that. Every time you bind a property in XAML, you're actually using a dependency property.

To make my point clearer, let's assume that you are writing a custom control. Other than the regular properties you get from inheriting from control, you...