[citation needed] The acronym is also used for any specific WSDL description of a web service (also referred to as a WSDL file), which provides a machine-readable description of how the service can be called, what parameters it expects, and what data structures it returns.

WSDL is often used in combination with SOAP and an XML Schema to provide Web services over the Internet.

A client program connecting to a Web service can read the WSDL file to determine what operations are available on the server.

The client can then use SOAP to actually call one of the operations listed in the WSDL file, using for example XML over HTTP.

By accepting binding to all the HTTP request methods (not only GET and POST as in version 1.1), the WSDL 2.0 specification offers better support for RESTful web services, and is much simpler to implement.

[2][3] However support for this specification is still poor in software development kits for Web Services which often offer tools only for WSDL 1.1.

WSDL 1.0 (Sept. 2000) was developed by IBM, Microsoft, and Ariba to describe Web Services for their SOAP toolkit.

[6] To mitigate vulnerability of these files, limiting access to generated WSDL files, setting proper access restrictions on WSDL definitions, and avoiding unnecessary definitions in web services is encouraged.