Jabber is a free instant messaging system.

in this package you will find jabberd14, a message transport server based on an xml message routing infrastructure.

all this high-tech is simply used to provide you with your own im server. see http://www.jabberd.org/ for more details.

jabber supports connecting to aim, icq, irc, msn and a lot of others, so you can use all available im systems from one client.

this package does not provide a jabber/xmpp client. some clients are compared at http://en.wikipedia.org/wiki/list_of_jabber_client_software