The messaging protocol that grew from Jeremie Miller's 1999 Jabber project is XMPP.
XMPP stands for Extensible Messaging and Presence Protocol. Miller began developing Jabber in 1998 and released the first jabberd server in January 1999. The project used open-source software and XML streams to support instant messaging, presence information, contact lists, and communication between independent servers.
The Jabber community submitted its work to the Internet Engineering Task Force, which formed an XMPP working group in 2002. The core standards were published as RFC 3920 and RFC 3921 in October 2004. “Jabber” was the original project and technology name; XMPP became the standards-oriented name, partly to avoid confusion with commercial trademarks and companies.
XMPP is often confused with IRC because both can support online chat, but IRC predates it and has a different protocol model. MQTT is primarily a lightweight publish-subscribe protocol for constrained devices and telemetry, while SIP is used chiefly to establish and manage sessions such as voice and video calls. XMPP can support those broader applications through extensions, but its historical foundation is open, decentralized messaging and presence.