WSDL stands for Web service Description Language. WSDL is used to locate and describe web services. WSDL is written in XML. This is the key element to develop Web service.

WSDL is a document written in XML. The document describes a Web service. It specifies the location and the operations of the service. WSDL document should definitely have below tags defined.

Types: this elements describes the data types used by the web service
Message: this element describes the messages used by the web service
Port types: this element describes the operations performed by the web service
Binding: this element describes the communication protocols used by the web service
Service: this element describes the end points. An end point is a combination of binding and URI

<!-- WSDL definition structure -->
<definitions name="MathService" targetnamespace="" xmlns="">
<!-- abstract definitions -->
<types> ...
<message> ...
<porttype> ...

<!-- concrete definitions -->
<binding> ...
<service> ...