What is the definition of Web services ?

Web Services is a collection of protocols & Standards.

Used for exchanging data between applications and systems. Various
programming languages & software running on various platforms can use
web services to exchange data over computer networks. It Uses common Network Protocols such as HTTP, SOAP & XML.

Web service is a piece of business logic, located somewhere on the
internet, that is accessible through standard internet protocols such as
HTTP or SMTP.
Advantages of Web services:
–Web Services can be developed on any computed platform in any development environment.
–Web Services can be Reused.
–Web Services are Deployed over standard Internet technologies. This makes it possible to deploy Web Services even over the firewall to servers running on the Internet on the other side of the globe
–Ability to be synchronous or asynchronous. Asynchronous clients retrieve their result at a later point in time, while synchronous clients receive their result when the service is completed. Asynchronous capability is a key factor in enabling loosely coupled systems.