IM

A client/server messaging technology that is much like e-mail, but operates in near real time. Instant messaging originated in the 1970s on PLATO, a private online instructional system for schools and universities in the United States, and was popularized in 1996 by ICQ, an Israel-based company later acquired by AOL. (Note: Instant Message is a Service Mark ( SM ) of AOL.) There are now a number of public Web-based IM services and enterprise systems, all of which are proprietary, i.e., non-standard. IM users create, by mutual consent, closed user groups (CUGs), commonly known as buddy lists, of correspondents.As IM occurs in near real time, it is necessary that both correspondents in a given message session be online at the same time.Therefore, IM systems include a presence mechanism to advertise all users of the status (e.g., available or unavailable) of all other users. Some IM systems now support one-way messaging if the recipient is not online. In this mode, the recipient can access the message at a later time, much like an e-mail communication. IM features typically include presence, privacy, contact lists (buddy lists), attachments, and message history. Some systems also include text, voice, and video and conferencing, and even whiteboarding. See also client/server, CUG, e-mail, near-realtime, presence, proprietary, standard, and whiteboarding.