While using XMPP as an XML message passing system is becoming more and more common, the original use was using it for user-to-user chatting. With this use case, you'll want to use client software for accessing the service.
One common open source XMPP client is Pidgin. Pidgin was initially created as the GTK+ AIM client, or GAIM. Over time, gaim gained the ability to implement additional protocols via a plugin architecture. In 2007, gaim was renamed pidgin in response to the legal pressures from America Online, who owned a trademark on the name AIM.
Pidgin plugins can also implement other pieces of functionality including an implementation of the Off the Record (OTR) protocol, which allows for end-to-end encryption of chat messages layered over the underlying protocol.
In addition to making protocols available as plugins, Pidgin split its core chat functionality into a separate library called libpurple, which was then adopted by other client implementations as...
