Web services are exposed components of a remote application over a network. Typically web services communicate over the HTTP and HTTPS protocols which are also the standard protocol for accessing web pages on the Internet. These exposed components are self-contained and are self-describing. Due to web services independence, they can be called by any application as long as it can be accessed via the network. Web services allow for a lot of flexibility when connecting two distinct systems because the service works independently from the client. In this case a web services built with Java in a UNIX environment not will have problems handling request from a C# application in a windows environment. This is because these systems are communicating over an open protocol allowed by both environments. Additionally web services can be found by using UDDI.
Colan, M. (2004). Service-Oriented Architecture expands the vision of web services, Part 1. Retrieved on August 21, 2011 from http://www.ibm.com/developerworks/library/ws-soaintro/index.html
W3Schools.com. (2011). Web Services Introduction - What is Web Services. Retrieved on August 21, 2011 from http://www.w3schools.com/webservices/ws_intro.asp