Some of the internet’s coolest new businesses are based on a technology older than the web

Its hallmarks are everywhere. Twitter’s @username convention began there; so did its use of # to denote topics. A new generation of chat software—such as Slack and Hipchat, which businesses use for internal communication, and GroupMe, one of the first apps to make group text messaging possible—are based on its principles. It was born in 1988, it predates the web, and it’s called Internet Relay Chat—IRC.

IRC is a virtual chatroom that users worldwide can join. Jarkko Oikarinen wrote the first IRC client and set up the first server at the University of Oulu in Finland in 1988. The code was released, and other servers were set up. IRC doesn’t require much bandwidth, and is very reliable. It was and remains popular with web developers. And because it’s been around so long, lots of tools have been developed on top of it, says Andy “Termie” Smith, a developer who’s worked at Google, Rackspace, Jaiku and Openstack. And while it’s not a mass phenomenon, it’s still considerable: At any one time, half a million or more users are chatting on it.

Because IRC is so old, it isn’t ideal for most people. It may not be entirely secure. The configuration to start using it is arcane. But as people’s email inboxes grow ever more unmanageable, there’s been growing demand for chat as a simpler, cleaner form of communication. Slack, a startup currently getting a lot of love from the tech community, is essentially an updated IRC for less-geeky users. Slack was born from an IRC chatroom—one its developers were using when they were creating a game called Glitch. As Mat Honan recently wrote in Wired, the game failed, but the chatroom took off.

“When we shut the game down we were thinking about what we could do next,” Cal Henderson, a co-founder and vice president of engineering at Slack, told Quartz. “We realized we didn’t want to work at a company without realtime multiuser chat.” Since Slack’s debut in February, it has made $1.5 million in revenue and raised $60 in venture capital, according to Wired, and powers internal communication at the likes of HBO, eBay, and the Wall Street Journal (as well as Quartz).

IRC’s efficiency was also what Twitter was aiming for in the beginning, Chris Messina—a developer credited with introducing the hashtag to Twitter (paywall)—told Quartz. In the tight 140-character limit of a tweet, hashtags made it easy to organize content by subject matter. And in the site’s early days, when mobile internet coverage was patchy, a user could subscribe to a hashtag (say, #sxsw, for the South By Southwest tech conference) and get all tweets with that hashtag sent as text messages.

But though new apps have been built, IRC isn’t gone. For budding software engineers, it’s an equalizer that can help them get into the profession. “Whatever you’re working on, there’s an IRC channel for it,” Smith said. “A dude who’s running a company and a 14-year-old are on equal footing, if they’re both asking relevant questions.”

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