Providers are highly customized solutions met to meet a particular need that any existing provider, or other component, doesn't compare up to.  If developed with flexibility, custom providers can be very useful, not only in the original application, but in an application framework as well.  The key object types that make up the provider are the abstract class, the derived classes with the implementation-specific logic (for instance, connecting to a database, text file, etc.), the configuration section, and a static class that exposes the provider to the consumer.  The abstract class is a key component, because it makes all of the providers available to the static class.  All of the derived classes can implement their own functionality using the signature of the abstract class, meaning using all of the abstract methods, properties, and events.  The configuration section informs the static class which provider to use as the default.  The static class exposes the default provider to the consumer, being able to switch easily between providers because they all inherit from the same abstract interface.  In addition, custom controls can wrap the functionality inside them, making any interface with the API a simple dragging and dropping of the controls.