Twitter hashtags are 10 years old and they wouldn't have happened without old-school texting

Yes, it's really been 10 years.

Twitter's most iconic feature is celebrating a big birthday today. Exactly 10 years ago, before there were iPhones, Android phones, or a Twitter app, one Twitter user came up with the idea of using the "#" symbol to group tweets together.

That early Twitter user was Chris Messina, who has said the idea originally stemmed from what are now two major throwbacks from the early days of the Internet: IRC and T-9.

IRC, or Internet Relay Chat, is an old web standard that enabled messaging via group chat rooms. The format we now know as a hashtag, where similar messages are grouped together using the # sign, was already a well-established part of IRC in 2007, so it made some sense to bring the same dynamic to Twitter.

It was also, as Messina points out, easier to type on old phones that used T-9, an early form of predictive text when you still had to tap out messages via your phone's keypad. (Texting was hard before touchscreens!)

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More surprising though, is that Twitter's founders came close to ignoring the idea completely. Before he had sent that first hashtagged tweet, Messina showed up at Twitter's offices to pitch the idea to Twitter cofounder Biz Stone and a few other early employees.

"Because brevity is essential on Twitter, he suggested using the 'pound' or 'hash' character common on phones (this was pre-iPhone) to create groups of related Tweets," Stone recounted in a blog post published today.

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Unfortunately for Messina, Stone was more concerned with dealing with the site's frequent crashes, which famously plagued the service in its early days.

"It was an undeniably elegant proposal, but I really needed to get back to work. I turned back to my computer screen to help get Twitter back up and running, hurriedly ending the conversation with a sarcastic, 'Sure, we’ll get right on that,' ” Stone wrote.

Original image has been replaced. Credit: Mashable

Luckily for all of us, Messina brushed off the brushoff and tweeted out his idea anyway. It was awhile longer before Twitter's founders embraced the idea and starting officially supporting it. But they eventually added hyperlinks to the tags, which cemented their status as one of Twitter's most recognizable features.

Of course, the hashtag has evolved a lot since then. Today, Twitter users send more than 125 million hashtags a day, according to the company, which is celebrating the milestone with -- what else -- a dedicated hashtag and custom emoji.