what are web services

What are web services

Web services are the terms used when we are accessing the internet , basically everyone uses these services but the difference is that

some know  this and some other do not know this :
and html and xml are the basis of this services:
web services use open protocols for communicating, application protocols and they can be used by other components.
web services  platform uses elements like SOAP(simple object model),
WSDL(web services description language),
UDDI(universal description ,dicovery and integrations).