Many people were surprised to hear recently that ICQ -- theonce-popular instant messaging (IM) client -- will shut down on June 26. I suspect more people were surprised to hear that ICQ (supposedly short for "I Seek You") was still around.

Back in 1996, though, ICQ wasthe IM client. Launched by Mirabilis, ICQ was the first widely adopted IM client and -- by 2001 -- the cross-platform messaging service had more than 100 million accounts.

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ICQ was far from the first instant messaging tool. Initial inklings of modern instant messaging emerged in 1961 with MIT's Compatible Time-Sharing System (CTSS), which enabled up to 30 users to chat in real time. That was a huge deal in its day! 

A decade later, in 1971, Murray Turoff created the first dedicated "instant messaging" system, the Emergency Management Information Systems and Reference Index (EMISARI), for the US government. EMISARI let users send messages that would pop up on their co-workers' terminals.

Unix users started using IM with the introduction -- in 1983's 4.2 BSD Unix release -- of the talk command, which let them have real-time text conversations with others logged into the same or different Unix systems. That's when I learned about instant messaging and quickly became a dedicated user.

While superseded by many other IM systems, Unix talk remains the oldest IM system still in use. You'll find it in almost all Linux and Unix distributions.

You might have thought "talk" would, in turn, lead to Internet Relay Chat (IRC). I thought so, but a little digging led me to discover that Jarkko "WiZ" Oikarinen, a student at the University of Oulu in Finland, developed IRC to replace a program called MUT (MultiUser Talk) on his Bulletin Board System (BBS) OuluBox. His goal was to extend the BBS software to support real-time discussions similar to Usenet news, but in a more immediate format.

IRC introduced several key features -- revolutionary in their day -- that we continue using today. These include channels, real-time communication, and Bots and Scripts to automate tasks and enhance functionality.

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IRC is still with us today. Indeed, as we'll see, while it's mostly known and used in Linux and technical circles, IRC had an oversized influence on Slack. Yes, Slack owes many of its core concepts, such as channels, to IRC.

While all that was going on in technical circles, ICQ was showing the world that everyone could use and enjoy IM. In 1997, America Online (AOL) released its own wildly popular AOL Instant Messenger (AIM). By the mid-2000s, AIM's "buddy list" feature gave AOL more than half the IM market. (I used AIM a lot in those days.) Yahoo and Microsoft quickly followed, respectively, with Yahoo Messenger in 1998 and MSN Messenger in 1999.

IM was also growing up. By the early 2000s, IM evolved from being a tool for programmers and young people flirting with each other to putting on a suit and joining the business world. Business IM took its time to catch on, but today, the odds are good that you're using Slack's messaging service.

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The IM clients started adding one feature after another. Services allowed you to share files and photos, play games, and even do early -- and, truth to be told, pretty awful -- voice and video calling. 

If the 1990s and 2000s were a golden age for IM clients, there was one big problem: Too many IM clients. If your friend or co-worker was on one network, and you were on another, you couldn't talk to each other 

One solution was multiprotocol IM clients such as Cerulean Studios' Trillian for Windows, the open-source Gaim for Linux and Windows, and Epicware's open-source Fire for macOS. Unless you were seriously into instant messaging in the early 2000s, chances are you haven't heard of these. They declined as the IM services either shut down or were absorbed into larger platforms -- such as MSN Messenger merging into Skype -- and the rise of proprietary protocols made it increasingly difficult for third-party clients to keep up.

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Another solution was universal IM protocols. Unfortunately, open protocols such as Extensible Messaging and Presence Protocol (XMPP), aka Jabber, and Session Initiation Protocol (SIP) Instant Messaging and Presence Leveraging Extensions (SIMPLE) declined because companies wanted users to use only their proprietary protocol. The protocols are still around, but few IM services are using them. 

There was another problem with these multiprotocol and universal IM approaches: Users increasingly preferred integrated communication platforms that went beyond texting and added voice and video conferencing.

That's why many use the likes of Slack, Microsoft Teams, Google Meet, and Discord with their complex, integrated solutions. Of course, you still can't talk from one system to another -- but the vendors like it that way. 

Another factor, and the reason why ICQ is flying the white flag, was the rise of mobile devices and social media in the late 2000s, which eroded the dominance of the old desktop IM clients. Upstarts like Messenger in 2008, WhatsApp in 2009, Snapchat in 2011, and other mobile messaging-optimized apps superseded the older IM clients.

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By 2015, the messaging app WhatsApp alone handled over 30 billion messages per day, far outstripping traditional SMS texts. Stalwarts like AIM, which failed to adapt to mobile, saw their user base dwindle until AOL finally pulled the plug in 2017. Indeed, ICQ was the last of the big-time 1990s IM clients standing.

Today, messaging is dominated by mobile-first apps such as WeChat and Telegram. These apps offer features that desktop IM clients could only dream of, including high-quality voice calls, video chat, payments, location sharing, and more. Other popular apps, such as TikTok, combine social networking and IM.

As we bid farewell to ICQ, please remember to not get too attached to WhatsApp, Telegram, or even Slack. I've been using and writing about IM services since the 1980s. I've seen them come and go. Eventually, they all falter because their feature set doesn't keep up with the latest developments. Soon, we'll want augmented or virtual reality (AR/VR) enabled IM systems. 

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Here's another reason IM services disappear: People grow tired of being locked into one system when their buddies or partners switch to another system. Right now, for example, everyone I know uses Slack. According to market SEO analysis firm 6Sense, Slack doesn't even have the majority of the market: WhatsApp Business has 31.64% market share, Slack has 21.39%, and Microsoft Teams has 19.46%.

Stick around, folks. Today's IM services may yet join their ancestors, to be replaced, in turn, by another generation of IM clients. 

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