WSDL is a type of format that is meant to describe that network services come with different endpoints. The end-points may contain different information. For example, one endpoint may be document-oriented while the other one will be procedure-oriented. There are three different statements that can be considered true about this, first one is data type will be apparent. Second is it will state whether the format is a document or a procedure. Third is it will describe the elements of the operation that will take place. This is known to be very helpful for a lot of people.
The element defines the data type that are used by the web service.
The element defines the message format and protocol details for each port.
The element defines the data elements of an operation.