Windows® Communication Foundation (WCF) is an application programming interface in the .NET Framework for building service-oriented applications. Servers implement multiple services that can be consumed by multiple clients. Services are loosely coupled to each other.
Services typically have a WSDL interface (Web Services Description Language), which any WCF client can use to consume the service. A WCF client connects to a service via an endpoint. Each service exposes itself via one or more endpoints. An endpoint has an address, which is a URL specifying where the endpoint can be accessed, and binding properties that specify how the data will be transferred.
WCF is an end-to-end web service. Many of the advantages afforded by .NET Remoting—a wide selection of protocol interoperability, for instance—can be achieved with a WCF interface, in addition to having access to a richer, more flexible set of native data types. .NET Remoting can only support native objects.
WCF offers more robust choices in most every aspect of web-based development, even implementation of a Java® client, for example.
For up-to-date information regarding WCF, see What Is Windows Communication Foundation on the Microsoft® webpage.