Web services are platform-independent interfaces based on well-understood internet protocols and standards. Web services enable any system within an IT infrastructure to send requests and receive responses from any other system, analogous to the way two people who speak the same language can send and receive mail by “standard” postal delivery service.
In this analogy, the people are any two computers on a network. The language in which the letter is written is XML (eXtensible Markup Language). The grammar and syntax used to compose the letter is WSDL (Web Services Definition Language).
The envelope in which the letter is sealed is SOAP (Simple Object Access Protocol). And the postal system or courier service is HTTP (HyperText Transport Protocol) or HTTPS (a secure form of HTTP).
