[frostwhale]

Correct me if I'm wrong, but it dates back to C? And # is used as includes / other first compiler steps? And the hashtag on twitter is a reference to this.

[Scown]

An early Twitter user suggested using hashtags, think he's generally credited with it:

http://factoryjoe.com/blog/2007/08/25/groups-for-twitter-or-...

[corrigible]

I was under the impression that it was popularized by IRC #channels

[reitanqild]

Twitter hashtags has obvious similarities and differences to IRC channels.

However I have a strong feeling that I modified/used hashtags (as tagging, not as a channel) back in 2005/6.

I think I got the idea from another system (probably some early wiki) but I'm unable to recall now.

[kardos]

I thought it was to make keyword searches work on twitter

[cmrdporcupine]

Sure but that notation looks obviously inspired by IRC to me.

[fernandotakai]

when i started using twitter back in 2008, that's how it felt to me -- that # tags were basically irc rooms and twitter itself was just a big async irc

[galdosdi]

I doubt that. The meaning of # in C does my resemble hashtags at all.

I would guess it was inspired by IRC, the first popular chat system, dating back to the 70s or 80s, which uses channels named with the hashmark and which are often named after the conversation topic

[galdosdi]

Edit: the meaning of # in C does not resemble hashtags at all. Typo.

[Terretta]

Don’t forget HTML fragment identifier:

https://en.m.wikipedia.org/wiki/Fragment_identifier#Basics

#Basics