When used in computing, a protocol is a convention or standard that controls or enables the connection, communication, and data transfer between two computing devices. Protocols may be implemented by hardware, software, or a combination of the two.
The wide-spread use and expansion of protocols is both a prerequisite to the Internet, and a major contributor to its power and success. The Transmission Control Protocol (or TCP) was the first of these, and the term TCP-IP refers to an important collection of the most used protocols. Most communication protocols are established in the RFC documents of the Internet Engineering Task Force or IETF.
Jabber implements the Extensible Messaging and Presence Protocol (XMPP).
This is an Open Protocol currently on the fast track to becoming an official Internet Standard through an IETF Working Group.