What is IDL?

Question

What is meant by IDL? I have googled it, and found out it stands for Interface Definition Language, which is used for interface definition for components. But, in practice,

Answer 1

It defines the interface to be used for communication with an exposed service in another application.

If you use SOAP you'll know about WSDL. The WSDL is another form of an IDL. IDL usually refers to Microsoft COM or CORBA IDL.