The following are the terms used in WCF
A message contains data which consist of body and headers.
A service is a construct which exposes one or more endpoints. Each endpoint exposing one or more service operations.
Endpoint contains a location (an address) that defines where messages can be sent, a specification of communication mechanism(a binding) that describes how messages should be sent.
An address specifies the location where messages are received. It is specified as a URI.
A service operation is a procedure defines in a services’s code that implements the functionality for an operation. This operation is exposed to clients as methods on a WCF client.
A service must be hosted in some process which include IIS, WAS(windows activation service) and windows services.
A WCF client is client-application that exposes the service operations as methods.A WCF client can be automatically generated by using the ServiceModel Metadata Utility Tool (Svcutil.exe) and pointing it at a running service that publishes metadata.