Jabber is a free instant messaging system.

in this package you will find the jabberd14 headers needed for building jabberd14 plugins e.g. transports.

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.