Learn to program using interfaces by reading C# Online.NET articles like Interfaces and Abstract Classes.
And, here is an excerpt from a VSLive! article on Interface-Based Programming in C#.
"Interfaces help define a contract, or agreement, between your application and other objects. This agreement indicates what sort of methods, properties and events are exposed by an object. But interfaces can be utilized for much more. Here, we’ll look at how interfaces can help make your applications and components easier to test." Read the rest of the article.
