XML
eXtensible Markup Language – A flexible way to create common information formats and share both the format and the data on the Web, intranets, and elsewhere.
XMPP
XMPP (Extensible Messaging and Presence Protocol) is a protocol based on Extensible Markup Language (XML) and intended for instant messaging (IM) and online presence detection. It functions between or among servers, and facilitates near-real-time operation. Currently, real-time search engines have adopted the XMPP protocol over traditional HTTP to render up to the second results.
