I'm trying to figure out how to use a Telerik ListBox control for an application that I'm writing. For some reason I can't view any of the Telerik demos (they're all timing out on me), and so I've been searching around this site for other help. I came across this page on drag-and-drop for the ListBox, and it looks really promising. However, in reading through the code on the page I came across their ProductToOrderConverter class. It inherits (or implements, I'm not sure which) from something called a DataConverter. What is that?? Even on this site I'm having a hard time finding any documentation on what the dataconverter class/interface is.