Definition: Instant messaging (or IM) offers users the ability to communicate in real time. Starting with IRC (Internet Relay Chat) users became hooked on the ability to "chat" in real time rather than sending emails back and forth or posting to a forum or message board.
Online service providers like America Online (AOL) and Compuserve created proprietary messaging systems that allowed users to see when their buddies were online and available to chat (as long as they use the same instant messaging software). ICQ introduced an IM system that was not tied to a particular ISP and that kicked off the mainstream popularity of Instant Messaging.
Also Known As: IM