A Web service is a method of communication between two electronic devices over a network. It is a software function provided at a network address over the Web with the service always on as in the concept of utility computing. The W3C defines a Web service generally as:
a software system designed to support interoperable machine-to-machine interaction over a network.
Web services resembles the website services that is provided for a domain, may it be a building of a new website or optimizing it for search engine ranking.
Web services often called application service, is a combination of programming and data available for web users and internet connected program, which is provided by the business web server.