Features in SharePoint designer 2010

hi, An interface looks like a class, but has no implementation. An interface contains only the signatures of methods, properties, events or indexers. A class or struct that implements the interface must implement the members of the interface that are specified in the interface definition. Please refer the link to know more about interface. http://msdn.microsoft.com/en-us/library/87d83y5b(v=VS.100).aspx

can you explain in detail?