As ubiquitous the hashtag is in today’s web, its full history is surprisingly sparsely documented. Most histories1 mention Twitter and the creator of its modern usage there, Chris Messina. He famously wrote back in 20072 “A Proposal for Twitter Tag Channels”. This was back in the day when people on the web also used terms like “folksonomy” with a straight face.

Few histories mention how the hash symbol was (and still is) used on IRC to denote the different channels and even fewer mention how these channels were also adopted by Jaiku3, Twitter’s competitor in the early “lifestreaming” social network scene. And that’s it. For example, in the Wikipedia article for hashtag, the term “jaiku” is nowhere to be seen4.

This is not to say that Messina didn’t create anything new. The real genius of Messina’s use, that separates it from its predecessors is this:

I’m more interested in simply having a better eavesdropping experience on Twitter.

The usage in Jaiku and IRC is a little bit different, but the humble hash symbol according to him did originate from these sources. So, the usage of the hash tag can be attributed to Messina but the origins lie deeper.

So, let’s go deeper. When did channels come to IRC? And more importantly, why are the IRC channels using #? While this post will ultimately fail to answer the latter question it should give enough resources for an interested reader to do more digging around the digital archives that still might exist and have not yet been lost to the ages.

The Short History of IRC’s Usage of Hash Symbol

My main motivation for this article was to find out if the hashtag has actually Finnish beginnings. After all, like Jaiku’s Jyri Engeström, IRC’s creator, Jarkko Oikarinen, is Finnish.

"A drunken naked man full of national pride running with a Finnish flag and a can of beer"

IRC wasn’t the first chat system and Wikipedia and the various histories around the internet list BITNET Relay, rmsg, DECnet phone, and MUT (of which very little is known except that it “had a bad habit of not working properly”) as the inspirations. However, none of these had named channels to my knowledge.

The listed inspirations are all either user-to-user or used numerical channels. IRC itself had numerical channels in the beginning5 and only got “string channels” later on.

One of the most notable characteristics of the IRC (Internet Relay Chat) protocol is to allow for users to be grouped in forums, called channels, providing a mean for multiple users to communicate together.

There was originally a unique type of channels, but with the years, new types appeared either as a response to a need, or for experimental purposes. (Internet Relay Chat: Channel Management)

The US became more aware of IRC during the Gulf War, or the “first media war”, when “in early 1991, live reports were available”6 through the IRC channel +report. Noteworthy here is the plus-sign as the prefix for the channel. These string channels were added in IRCd 2.57 on 20th June 1990. The more familiar “#channels” with hash prefix came a bit over half a year later in 2.68 on 20th February 1991:

IRC 2.6 has multiple channels, ie. channels beginning with ‘#’-character. These channels are specific in the sense that people can join several of them simultaneusly [sic] and take part in several conversations.

All three channel types apparently co-existed until version 2.7 when both numerical and “+channels” were replaced by “#channels”.

Interpreting the Tao of IRC seems to indicate that the change from + to # as the channel prefix might have been due to the ambiguity of IRC already using + to mark the various modes of a channel. But why # instead of some other symbol? Probably because many of the other popular symbols were already in use.

A more complete history of the hashtag would try ask Oikarinen why he chose # as the symbol for channels. It is entirely possible that the choice of the symbol was discussed in chat logs now lost to time and he was only the first to implement its usage as a marker of topic for discussion.

After all, the more traditional role of # in computing has been to make things invisible to the user, to comment out stuff.

Who came up with the name “hashtag”?

The etymology of “hashtag” is not as clear. Famously, Messina called # “pound” in his tweet. In “Why’s It Called a Hashtag?” J. Kevin Wolfe asked Messina about the origin of the term.

He proposed the name “channel tags.” He was kind enough to do a search and found a 2007 message where Stowe Boyd called them hashtags.

It is again entirely possible someone had called them “hashtags” in similar context (fe. on Jaiku) but this was as far as I was able to go.

Totally Incomplete Hashtag Timeline