The types element describes the different data types that will be used by your web service. A web service will usually have one or many input type, one or many output type and one or many fault type. And if the web service has many functions (operations) declares, each one could have their own set of input type, output type and fault type.

Data types could be declares in any language as long as the web service supports it, but they are usually specified XML Schema.

The following is an example of the types element in a WSDL 2.0 file. 

<types>
    <xs:schema
        xmlns:xs = "http://www.w3.org/2001/XMLSchema"
        targetNamespace = "http://yoursite.com/MyService/schema"
        xmlns = "http://yoursite.com/MyService/schema" >
      <xs:element name="checkServiceStatus" type="tCheckServiceStatus" />
      <xs:complexType name="tCheckServiceStatus" >
        <xs:sequence>
          <xs:element name = "checkDate" type = "xs:date" />
          <xs:element name = "serviceName" type = "xs:string" />
        </xs:sequence>
      </xs:complexType>
      <xs:element name = " checkServiceStatusResponse" type = "xs:double" />
      <xs:element name = "dataError" type = "xs:string" />
    </xs:schema>
</types>