What is SOAP used for?

Taken from the SOAP v1.1 specification [http://www-4.ibm.com/software/developer/library/soap/soapv11.html:

SOAP is a lightweight protocol for exchange of information in a decentralized, distributed environment. It is an XML based protocol that consists of three parts: an envelope that defines a framework for describing what is in a message and how to process it, a set of encoding rules for expressing instances of application-defined datatypes, and a convention for representing remote procedure calls and responses.