The provider model is used throughout ASP.NET 2.0. It is a means of writing each of the technologies used so that new versions can easily be created and plugged in. For example, if you need to access a different database or authentication server, you can create a provider for it. ASP.NET 2.0 will then work with that provider just as it works with the existing features. This makes ASP.NET 2.0 much more flexible, expandable, and customizable than before.

http://msdn.microsoft.com/asp.net/downloads/providers/default.aspx