what are end points, contract, address and bindings?

The above terminologies are the core on which SOA stands. Every service must expose one or more end points by which the service can be available to the client. End point consists of three important things where, what and how:

Contract (What) Contract is an agreement between two or more parties. It defines the protocol how client should communicate with your service. Technically it describes parameters and return values for a method.
Address ( Where) An Address indicates where we can find this service. Address is a URL which points to the location of the service.
Binding (How) Bindings determine how this end point can be accessed. It determines how communications is done. For instance you expose your service which can be accessed using SOAP over HTTP or BINARY over TCP. So for each of these communications medium two bindings will be created.
Below figure show the three main components of end point. You can see the stock ticker is the service class which has an end point hosted on www.soa.com with HTTP and TCP binding support and using Stock Ticker interface type.

Figure 15.3 : - Endpoint Architecture