protocol: n. As used by hackers, this never refers to niceties about the proper form for addressing letters to the Papal Nuncio or the order in which one should use the forks in a Russian-style place setting;

:protocol: n. As used by hackers, this never refers to niceties
about the proper form for addressing letters to the Papal Nuncio or
the order in which one should use the forks in a Russian-style
place setting; hackers don't care about such things. It is used
instead to describe any set of rules that allow different machines
or pieces of software to coordinate with each other without
ambiguity. So, for example, it does include niceties about the
proper form for addressing packets on a network or the order in
which one should use the forks in the Dining Philosophers Problem.
It implies that there is some common message format and an accepted
set of primitives or commands that all parties involved understand,
and that transactions among them follow predictable logical
sequences. See also {handshaking}, {do protocol}.
-- The AI Hackers Dictionary