SOAP is a protocol used in computing. Web services use this protocol to communicate. SOAP uses XML to encode a message. It uses other application-layer protocols, for transport, and content negotiation, for example HTTP and Remote procedure call. The most common combination is to use SOAP with HTTP and TCP. There are different versions, 1.0, 1.1, and 1.2. Before version 1.2 SOAP stood for Simple Object Access Protocol. Since version 1.2 the protocol is simply called "SOAP". This is because the protocol is not "simple", and that it can be used for other purposes than accessing objects. 