<!-- WSDL definition structure -->
<definitions
name="MathService"
targetNamespace="http://example.org/math/"
xmlns="http://schemas.xmlsoap.org/wsdl/"
>
<!-- abstract definitions -->
<types> ...
<message> ...
<portType> ...

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

what is "abstract definitions" and "concrete definitions" here!!!

Can some one explain please.