Window Communication Foundation is popularly known as WCF.WCF is basically a Programming framework that are used to built applications that can inter communicate with each others .WCF basically belongs to .NET Framework used for communication .

WCF is part of newly introduced application programming interface in .NET Framework 3.0.
WCF service

A WCF Service consists of 3 parts
1) Service class that implements the service to be provided.
2) Host Environment to host the service.
3) One or more Endpoints to which clients can communicate.

Any of the communication through WCF will happen through Endpoints.Endpoints calls for a contract that defines which methods of service class will be available via Endpoints.

Each endpoints consists of different set of methods. The endpoints also define a binding that specifies how a client will communicate with the service and the address where the endpoint is hosted.

WCF states about Windows Activation Services which is WCF can be used to host The WCF Service .If this is not the case then WCF can be hosted in IIS or in any other process by using Service Host Class.