A communication protocol is a system of rules that allows two or more entities of a communications system to transmit information via any kind of variation of a physical quantity. The protocol defines the rules, syntax, semantics and synchronization of communication and possible error recovery methods. Protocols may be implemented by hardware, software, or a combination of both.
“Protocols” from the Lab Book of the Civic Laboratory for Environmental Action Research (CLEAR):
Protocols are the “attitudes” or “the manner in which one approaches each and every element in our space.” They are different than pure rules or instructions; they are ways that we establish order and maintain practices across our group […] – They define the way we ought to proceed or behave in different situations. As such, they are normative, or premised on values, morals, and an idea of how things ought to be done. They are a manifestation of our values.