How Do I: Use Attached Properties to Store Extra Data in WPF
If you've ever found yourself storing extra data in a control's Tag property because you just couldn't find anywhere to put it, this video is for you. In it, Todd Miranda shows how to store extra data using Attached Properties.
An attached property is a concept defined by Extensible Application Markup Language (XAML). An attached property is intended to be used as a type of global property that is settable on any object. In Windows Presentation Foundation (WPF), attached properties are typically defined as a specialized form of dependency property that does not have the conventional property "wrapper" (MSDN).
By: Todd Miranda