Instant messaging

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Though the term dates from the 1990s, instant messaging predates the Internet, first appearing on multi-user operating systems like Compatible Time-Sharing System (CTSS) and Multiplexed Information and Computing Service (Multics) in the mid-1960s. Initially, some of these systems were used as notification systems for services like printing, but quickly were used to facilitate communication with other users logged into the same machine. CTSS facilitated communication via text message for up to 30 people.

Parallel to instant messaging were early online chat facilities, the earliest of which was Talkomatic (1973) on the PLATO system, which allowed 5 people to chat simultaneously on a 512 x 512 plasma display (5 lines of text + 1 status line per person). 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. The first such general-availability commercial online chat service (as opposed to PLATO, which was educational) was the CompuServe CB Simulator in 1980, created by CompuServe executive Alexander "Sandy" Trevor in Columbus, Ohio.

As networks developed, the protocols spread with the networks. Some of these used a peer-to-peer protocol (e.g. talk, ntalk and ytalk), while others required peers to connect to a server (see talker and IRC). The Zephyr Notification Service (still in use at some institutions) was invented at MIT's Project Athena in the 1980s to allow service providers to locate and send messages to users.

Early instant messaging programs were primarily real-time text, where characters appeared as they were typed. This includes the Unix "talk" command line program, which was popular in the 1980s and early 1990s. Some BBS chat programs (i.e. Celerity BBS) also used a similar interface. Modern implementations of real-time text also exist in instant messengers, such as AOL's Real-Time IM as an optional feature.

In the latter half of the 1980s and into the early 1990s, the Quantum Link online service for Commodore 64 computers offered user-to-user messages between concurrently connected customers, which they called "On-Line Messages" (or OLM for short), and later "FlashMail." Quantum Link later became America Online and made AOL Instant Messenger (AIM, discussed later). While the Quantum Link client software ran on a Commodore 64, using only the Commodore's PETSCII text-graphics, the screen was visually divided 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 type of graphical user interface (GUI), albeit much more primitive than the later Unix, Windows and Macintosh based GUI IM software. 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.

Development of the Internet Relay Chat (IRC) protocol began in 1988, and this would become the Internet's first widespread instant messaging standard.

Modern, Internet-wide, GUI-based messaging clients as they are known today, began to take off in the mid-1990s with PowWow, ICQ, and AOL Instant Messenger (AIM). Similar functionality was offered by CU-SeeMe in 1992; though primarily an audio/video chat link, users could also send textual messages to each other. AOL later acquired Mirabilis, the authors of ICQ; establishing dominance in the instant messaging market. A few years later ICQ (then owned by AOL) was awarded two patents for instant messaging by the U.S. patent office. Meanwhile, other companies developed their own software; (Excite, Microsoft (MSN), Ubique, and Yahoo!), 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. However, the open protocol IRC continued to be popular by the millennium, and its most popular graphical app was mIRC.

While instant messaging was mainly in use for consumer recreational purposes, in 1998, IBM launched their Lotus Sametime instant messenger software, the first popular example of enterprise-grade instant messaging. In 2000, an open-source application and open standards-based protocol called Extensible Messaging and Presence Protocol (XMPP) was launched, initially branded as Jabber. XMPP servers could act as gateways to other IM protocols, reducing the need to run multiple clients.

Video calling using a webcam also started taking off during this time. Microsoft's NetMeeting, which was focused on business "web conferencing", was one of the earliest; the company then launched Windows Messenger, coming preloaded on Windows XP, featuring video capabilities. Yahoo! Messenger added video capabilities in 2001; by 2005, such features were built-in also in AIM, MSN Messenger, and Skype.

There were a reported 100 million users of instant messaging in 2001. As of 2003, AIM was the globally most popular instant messenger with 195 million users and exchanges of 1.6 billion messages daily. By 2006, AIM controlled 52 percent of the instant messaging market, but rapidly declined shortly thereafter as the company struggled to compete with other services.

Instant messaging integrated in other services started picking up pace in the late 2000s. Myspace, the then-largest social networking service, launched Myspace IM in 2006, shortly after Google's Gtalk, which was integrated into its Gmail webmail interface. Facebook Chat launched in 2008, providing IM to users of the social network. By 2010, traditional instant messaging was in sharp decline in favor of these new messaging features on wider social networks, which at the time were not normally called IM. For instance, AIM's userbase had declined by more than half throughout the year 2011.

Standalone instant messenger services were revived, evolving into becoming primarily being used on mobile due to the increasing use of Internet-enabled cell phones and smartphones. Often called "chat apps", to distinguish it from cellular-based SMS and MMS "texting" services, these newer services were specially designed to be run on mobile platforms, as opposed to older services like AIM and MSN; BlackBerry Messenger, released in 2005, was one of the influential pioneers of mobile IM, and led to other companies launching services with proprietary protocols, such as WhatsApp. Mobile instant messaging surpassed SMS in global message volume by 2013. While SMS relied on traditional paid telephone services, IM apps on mobile were available for free or a minor data charge.

Older IM services were eventually shut, including AIM and Yahoo! Messenger, and also Windows Live Messenger, which merged into Skype in 2013. In 2014, it was reported that instant messaging had more users than social networks. Concurrently, rising use of instant messaging at workplaces led to the creation of new services (enterprise application integration (EAI)) often integrated with other enterprise applications such as workflow systems, for example in Skype for Business, Slack and Microsoft Teams. Meanwhile, the launch of Discord in 2015 has marked a notable new example of traditional IM originally designed for desktops.

Most IM protocols are proprietary and are not designed to be interoperable with others, meaning that many IM networks have been incompatible and users have been unable to reach users on other networks. As of 2024, fragmentation of IM services means that a typical user is likely to have to use more networks than ever, including the need to download the apps and signing up, to stay in touch with all their contacts. However, there had been attempts for solutions.

Multi-protocol clients can use any of the IM protocols by using additional local libraries for each protocol. Examples of multi-protocol instant messenger software include Pidgin and Trillian, and more recently Beeper. These third-party clients have often been unable to keep up due to proprietary protocol restrictions and getting locked out of it. For instance, in 2015, WhatsApp started banning users who were using unofficial clients. Major IM providers usually cite the need for formal agreements, and security concerns as reasons for making changes.

There have been several attempts in the past to create a unified standard for instant messaging, including:

• IETF's Session Initiation Protocol (SIP) and SIP for Instant Messaging and Presence Leveraging Extensions (SIMPLE)
• Application Exchange (APEX),
• Instant Messaging and Presence Protocol (IMPP),
• Extensible Messaging and Presence Protocol (XMPP), based on XML, and
• Open Mobile Alliance's Instant Messaging and Presence Service (IMPS), developed specifically for mobile devices.

In the early 2000s, when instant messaging was quickly growing, most attempts at producing a unified standard for the-then major IM providers (AOL, Yahoo!, Microsoft) had failed. There was a "bitter row" between AOL and its rivals regarding the opening up of their networks. In 2000, U.S. regulatory Federal Communications Commission (FCC) proposed, and supported by Microsoft chairman Bill Gates, that AOL providing interoperability of its AIM and ICQ instant messengers with Microsoft's MSN Messenger was a condition for the forthcoming AOL-Time Warner merger.

However, in 2004, Microsoft, Yahoo! and AOL agreed to a deal in which Microsoft's enterprise IM server Live Communications Server 2005 would have the possibility to talk to their rival counterparts and vice versa. On October 13, 2005, Microsoft and Yahoo! announced that their IM networks would soon be interoperable, using SIP/SIMPLE. This was finally rolled out to Windows Live Messenger and Yahoo! Messenger users in July 2006. Additionally, in December 2005 by the AOL and Google strategic partnership deal, it was announced that AIM and ICQ users would be able to communicate with Google Talk users. However this feature took until December 2007 to roll out. XMPP provided the best example of open protocol interoperability, having had gateways that connected to Google Talk, Lotus Sametime and others.

Later, RCS was developed by telecommunication companies as an instant messaging protocol to replace SMS under a unified standard. In 2022, the European Union passed the Digital Markets Act, which largely came into effect in early 2023. Among other things, the legislation mandates certain interoperability between the largest IM platforms in use in Europe. As a result, in March 2024, Meta Platforms opened up its WhatsApp and Messenger networks to be interoperable.

There are two ways to combine the many disparate protocols:

• Combine the many disparate protocols inside the IM client application.
• Combine the many disparate protocols inside the IM server application. This approach moves the task of communicating with the other services to the server. Clients need not know or care about other IM protocols. For example, LCS 2005 Public IM Connectivity. This approach is popular in XMPP servers; however, the so-called transport projects suffer the same reverse engineering difficulties as any other project involved with closed protocols or formats.

Some approaches allow organizations to deploy their own, private instant messaging network by enabling them to restrict 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 an encrypted, firewall-friendly, HTTPS-based protocol. Usually, a dedicated corporate IM server has several advantages, such as pre-populated contact lists, integrated authentication, and better security and privacy.

Instant messaging has changed how people communicate in the workplace. Enterprise messaging applications like Slack, Symphony, Teamnote and Yammer allow companies to enforce policies on how employees message at work and ensure secure storage of sensitive data. They allow employees to separate work information from their personal emails and texts.

Messaging applications may make workplace communication efficient, but they can also have consequences on productivity. A study at Slack showed on average, people spend 10 hours a day on Slack, which is about 67% more time than they spend using email.

Instant messaging is implemented in many video-conferencing tools. A study of chat use during work-related videoconferencing found that chat during meetings allows participants to communicate without interrupting the meeting, plan action around common resources, and enables greater inclusion. The study also found that chat can cause distractions and information asymmetries between participants.

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