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 (AOL), offers a similar product under the name "AOL Instant Messages" (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.
Modern, Internet-wide, GUI-based messaging clients, as they are known today, began to take off in the mid 1990s with ICQ (1996) being the first, followed by AOL Instant Messenger (AOL Instant Messenger, 1997). AOL later acquired Mirabilis, the creators of ICQ. A few years later ICQ (by now owned by AOL) was awarded two patents for instant messaging by the U.S. patent office. Meanwhile, other companies developed their own applications (Yahoo, MSN, Excite, Ubique, IBM), each with its own proprietary protocol and client; users therefore had to run multiple client applications if they wished to use more than one of these networks.
In 2000, an open source application and open standards-based protocol called Jabber was launched. Jabber servers could act as gateways to other IM protocols, reducing the need to run multiple clients. Modern multi-protocol clients such as Pidgin, Trillian, Adium and Miranda can use any of the popular IM protocols without the need for a server gateway.
Recently, many instant messaging services have begun to offer video conferencing features, Voice Over IP (VoIP) and web conferencing services. Web conferencing services integrate both video conferencing and instant messaging capabilities. Some newer instant messaging companies are offering desktop sharing, IP radio, and IPTV to the voice and video features.
The term "instant messenger" is a service mark of Time Warner and may not be used in software not affiliated with AOL in the United States. For this reason, the instant messaging client formerly known as Gaim or gaim announced in April 2007 that they would be renamed "Pidgin".
There have been several attempts to create a unified standard for instant messaging: IETF's SIP (Session Initiation Protocol) and SIMPLE (SIP for Instant Messaging and Presence Leveraging Extensions), APEX (Application Exchange), Prim (Presence and Instant Messaging Protocol), the open XML-based XMPP (Extensible Messaging and Presence Protocol), more commonly known as Jabber and OMA's (Open Mobile Alliance) IMPS (Instant Messaging and Presence Service) created specifically for mobile devices.
Sometimes, companies have tried to make one standard for all major IM providers (AOL, Yahoo! and Microsoft). These have not worked out, so each still uses its own proprietary protocol.
However, while discussions at IETF were stalled, Reuters head of collaboration services, David Gurle (the founder of Microsoft's Real Time Communication and Collaboration business), surprised everybody by signing the first inter-service provider connectivity agreement in September 2003. This historic agreement enabled AIM, ICQ and MSN Messenger users to talk with Reuters Messaging counterparts and vice-versa against an access fee. Following this breakthrough agreement between networks Microsoft, Yahoo! and AOL came to a deal where Microsoft's Live Communication Server 2005 (which is interestingly also used by Reuters for its Reuters Messaging service) users would also have the possibility to talk to public instant messaging users. This deal settled once for all the protocol for interconnectivity in the market as SIP/SIMPLE and established a connectivity fee for accessing public instant messaging clouds. Separately, on October 13, 2005 Microsoft and Yahoo! announced that by (the Northern Hemisphere) summer of 2006 they would interoperate using SIP/SIMPLE which is followed on December 2005 by the AOL and Google strategic partnership deal where Google Talk users would be able to talk with AIM and ICQ users provided they have an identity at AOL.
There are two ways to combine the many disparate protocols:
Some approaches, such as that adopted by the Sonork enterprise IM software or the Jabber/XMPP network or Winpopup LAN Messenger, allow organizations to create their own private instant messaging network by enabling them to limit access to the server (often with the IM network entirely behind their firewall) and administer user permissions. Other corporate messaging systems allow registered users to also connect from outside the corporation LAN, by using a secure firewall-friendly HTTPS based protocol. Typically, a dedicated corporate IM server has several advantages such as pre-populated contact lists, integrated authentication, and better security and privacy.
Some networks have made changes to prevent them from being utilized by such multi-network IM clients. For example, Trillian had to release several revisions and patches to allow its users to access the MSN, AOL, and Yahoo! networks, after changes were made to these networks. The major IM providers typically cite the need for formal agreements as well as security concerns as reasons for making these changes.
Mobile Instant Messaging (MIM) is a presence enabled messaging service that aims to transpose the desktop messaging experience to the usage scenario of being on the move. While several of the core ideas of the desktop experience on one hand apply to a connected mobile device, others do not: Users usually only look at their phone's screen — presence status changes might occur under different circumstances as happens at the desktop, and several functional limits exist based on the fact that the vast majority of mobile communication devices are chosen by their users to fit into the palm of their hand.
Some of the form factor and mobility related differences need to be taken into account in order to create a really adequate, powerful and yet convenient mobile experience: radio bandwidth, memory size, availability of media formats, keypad based input, screen output, CPU performance and battery power are core issues that desktop device users and even nomadic users with connected notebooks are usually not exposed to.
Several formerly untackled issues have been identified and addressed within IMPS, which was developed as part of an early mobile telephone industry initiative to kick off a broader usage of mobile instant messaging. The Open Mobile Alliance has taken over this standard, formerly called Wireless Village, as IMPS V1.0 in November 2002. Since then this standards has been further developed to IMPS V1.3, the latest candidate for release, and is expected to be released before the end of 2006.
There are downloadable mobile applications offered by different independent developers that allow users to chat within public (MSN, Yahoo!, Google Talk, AIM, ICQ) and corporate (LCS, Sametime, Reuters) IM services from mobile devices.
Among the advantages of using such IM clients over SMS are: IM clients use data instead of SMS text messages; IM-like chat mode, faster and quicker messaging. Some IM software allows group communication.