WCF is Windows Communication foundation for developing services. The supported protocols are TCP, HTTP, msmq etc

Please check following link, it is really nice explanation about WCF in detail.http://www.c-sharpcorner.com/UploadFile/akrtripathi/an-introduction-to-windows-communication-foundation-wcf/

Windows Communication Foundation (WCF) is an SDK for developing and deploying services on Windows. WCF provides a runtime environment for services, enabling you to expose CLR types as services, and to consume other services as CLR types.
WCF is part of .NET 3.0 and requires .NET 2.0, so it can only run on systems that support it.