An open standard for instant messaging (IM). There are tens of thousands of Jabber servers on the Internet, most of which are privately run within a company or college campus. There are also hundreds of public Jabber servers that any user can register with, Google Talk being the largest.

Jabber uses the XMPP protocol, and any IM client program that supports XMPP can communicate with any other user who has an XMPP client, providing the sender is in the recipient's contact list (buddy list). Multi-protocol IM clients support XMPP along with proprietary IM services such as AOL/AIM, ICQ, MSN and Yahoo!; however, an IM account must be opened with each service.

There are numerous open source implementations of Jabber clients and servers. For more information, visit www.jabber.org.

Instant E-Mail
The Jabber architecture is like e-mail with users communicating from domain to domain. For example, a Jabber server at computerlanguage.com can connect with the Jabber server at gmail.com (Google's IM domain). Jabber also supports access to non-XMPP systems by connecting a "transport" to the Jabber server that provides a gateway to that IM protocol. However, if a public Jabber server with thousands of users employs a gateway, chances are the proprietary IM service will eventually block its IP address, since a huge amount of traffic coming from one IP address is generally not tolerated.

Enterprise Jabber
There are several commercial implementations of Jabber, the most notable of which are from Jabber, Inc., Denver, CO (www.jabber.com). Founded in 2000, soon after Jabber was developed, Jabber, Inc. offers client, server and appliance versions of Jabber. For example, supporting thousands of users, Jabber XCP is a widely used secure enterprise server. In 2008, the company was acquired by Cisco. See instant messaging, Google Talk and XMPP.