Jabber is radically different from all other instant messaging systems that it really cannot be likened unto systems such as ICQ or AIM. It really is more like an e-mail client in that you must have an account with a system and that you can use any client you want to connect to your server. Using XML as the base, Jabber clients connect to a Jabber server to communicate to other systems. The modular server handles all communication to outside systems and to other Jabber systems. The client itself only needs to connect to the Jabber server and from then on it does not concern itself with what type of clients it is exchanging information with. The Jabber server translates the proprietary protocols that systems like Yahoo! Pager, or Mirabilis ICQ use so that the messages are sent using an open XML standard. None of the features of these systems are lost using Jabber - you only gain more choices and options.