Instant messaging (IM) is a form of real-time communication between two or more people based on typed text. The text is conveyed via computers connected over a network such as the Internet.

Overview

Instant messaging (IM) and chat are technologies that create the possibility of real-time text-based communication between two or more participants over the internet or some form of internal network/ intranet. It is important to understand that what separates chat and instant messaging from technologies such as e-mail is the perceived synchronicity of the communication by the user - Chat happens in real-time before your eyes. Some systems allow the sending of messages to people not currently logged on (offline messages), thus removing much of the difference between Instant Messaging and e-mail.

While many services have additional features such as: the immediate receipt of acknowledgment or reply, group chatting, conference services (including voice and video), conversation logging and file transfer, those functions are beyond the scope of this article.

IM allows effective and efficient communication, featuring immediate receipt of acknowledgment or reply. In certain cases Instant Messaging involves additional features, which make it even more popular, i.e. to see the other party, e.g. by using web-cams, or to talk directly for free over the Internet.

It is possible to save a conversation for later reference. Instant messages are typically logged in a local message history which closes the gap to the persistent nature of e-mails and facilitates quick exchange of information like URLs or document snippets (which can be unwieldy when communicated via telephone).

History

Instant messaging actually predates the Internet, first appearing on multi-user operating systems like CTSS and Multics in the mid-1960s. Initially, many of these systems, such as CTSS'.SAVED, were used as notification systems for services like printing, but quickly were used to facilitate communication with other users logged in to the same machine. As networks developed, the protocols spread with the networks. Some of these used a peer-to-peer protocol (eg talk, ntalk and ytalk), while others required peers to connect to a server (see talker and IRC). During the Bulletin board system (BBS) phenomenon that peaked during the 1980s, some systems incorporated chat features which were similar to instant messaging; Freelancin' Roundtable was one prime example.

In the last half of the 1980s and into the early 1990s, the Quantum Link online service for Commodore 64 computers offered user-to-user messages between currently connected customers which they called "On-Line Messages" (or OLM for short). Quantum Link's better known later incarnation, America Online, offers a similar product under the name "AOL Instant Messenger" (AIM). While the Quantum Link service ran on a Commodore 64, using only the Commodore's PETSCII text-graphics, the screen was visually divided up into sections and OLMs would appear as a yellow bar saying "Message From:" and the name of the sender along with the message across the top of whatever the user was already doing, and presented a list of options for responding. As such, it could be considered a sort of GUI, albeit much more primitive than the later Unix, Windows and Macintosh based GUI IM programs. OLMs were what Q-Link called "Plus Services" meaning they charged an extra per-minute fee on top of the monthly Q-Link access costs.