In
networking, a protocol is the specification of a set of rules for a particular type of
communication.
Different protocols often describe different aspects of a single communication; taken together, these form a
protocol stack.
The terms "protocol" and "protocol stack" also refer to the software that implements a protocol.
Most recent protocols are assigned by the IETF for internet communications, and the IEEE, or the ISO organizations for other types. The ITU-T handles telecommunications protocols and formats.
In
international law and [international relations]
?, a protocol is a
treaty or [international agreement]
? that supplements a previous treaty or international agreement.
A protocol can amend the previous treaty, or add additional provisions.
Parties to the earlier agreement are not required to adopt the protocol; sometimes this is made clearer by calling it an 'optional protocol', especially where many parties to the first agreement do not support the protocol.
Some examples: the United Nations Framework Convention on Climate Change (UNFCC) established a framework for the development of binding greenhouse gas emission limits, while the Kyoto Protocol contained the limits later agreed upon.