Every service must have Address that defines where the service resides, Contract that defines what the service does and a Binding that defines how to communicate with the service.
In WCF the relationship between Address, Contract and Binding is called Endpoint, The Endpoint is the fusion of Address, Contract and Binding.
Address: Specifies the location of the service.
Contract: Specifies the interface between client and the server.
Binding: Specifies how the two parties will communicate in term of transport and encoding and protocols.