Also called "Chat Programs". These applications are installed on a PC by a user, and allow immediate "chats" between other users of the program. Some of these programs also allow audio or video conferencing as well as the ability to execute file transfers.
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digsby is a multiprotocol instant messenger client that allows a user to have AIM, MSN, Yahoo, ICQ, Google Talk, and Jabber buddy lists in one window. It also provides alerts to messages on various social networking sites.
