An endpoint is a combination of Address, Binding, and Contract (ABC's).In general, Endpoint is used to communicate from service to client and client to service.A WCF Service contains one or more endpoints. An endpoint is a construct at which message are to be sent or received and provides clients to access the functionality that WCF service  will offer.All type of communication with services will take place through end points only.A WCF Service should contain minimum one endpoint.

The address represents where to communicate and is used to locate where the service is available.In general a "URI" i.e. Uniform Resource Identifier which specifies where message sends and received. In general, each endpoint can have one or more addresses and each address can have a unique identification.

Binding specifies how to communicate with endpoint i.e. represents how to send and receive the messages. Binding also specifies what type of protocol is used and which type of security requirement as well as reliability.

In WCF, all services expose contracts. The contract is a platform neutral and strandard way of describing what the service does.

Hosting a service means, making the service run. So that service can take requests from the client and process those requests and deliver the response to the client.

The main goal of Channel is to transform the message to the format understandable by the communication wire and compatible to both server and client and then transport the message over the wire in between client and server.