According to Wikipedia, a "tunneling protocol" is:
when one network protocol (the delivery protocol) encapsulates a different payload protocol. By using tunneling one can (for example) carry a payload over an incompatible delivery-network, or provide a secure path through an untrusted network.
To me, this definition is rather vague. To me, I interpret this definition of tunneling as any time one protocol's payload is actually a request/response formatted for another protocol. Like if you took the binary of a TCP request and placed it in the body of an HTTP request.
Am I on track? If not please correct/clarify and provide some concrete examples. Thanks in advance!