A free protocol is a protocol whose full specification is freely available and for which there are no restrictions (e.g. legal or technical) on its use. Users may design and use variations that suit their needs, and contribute enhancements for potential incorporation into the next official version of the protocol. A free software

Free software

Free software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions that only ensure that further recipients can also do...

 reference implementation

Reference implementation

In the software development process, a reference implementation is the standard from which all other implementations, with their attendant customizations, are measured, and to which all improvements are added...

 must be available.

Free protocol are important for interoperability and choice of software.

XMPP

Extensible Messaging and Presence Protocol

Extensible Messaging and Presence Protocol is an open-standard communications protocol for message-oriented middleware based on XML . The protocol was originally named Jabber, and was developed by the Jabber open-source community in 1999 for near-real-time, extensible instant messaging , presence...

 is a free protocol.

See also

• open standard
  Open standard
  An open standard is a standard that is publicly available and has various rights to use associated with it, and may also have various properties of how it was designed . There is no single definition and interpretations vary with usage....
  
  
• free file format