The journey of the hashtag is long and storied – it saw many lives before it became the powerful organizer of tweets by topic. Like many of the other symbols, its first known use too was by the Romans.
Its origins started with the Roman use of the short form “lb” for libra pondo or “pound in weight.” Eventually, with its use in English, and as people started writing faster, a line was placed across the lb until it started to look like #.
The # was included as a character in printers, though it continued to be called pound sign. And then in the 1870s it reached the typewriter (often on the 3 key).
The # symbol saw another life as an octothorpe when it got included on the telephone keypad. It was this inclusion on the phone keypad that made it a well-known symbol to the general public. The # on the phone started to signify numbers in automated customer service systems, and it would have stayed like that forever, had it not been for Chris Messina’s attempt to organize Twitter.
Looking for a way to organize twitter by topicality, Chris Messina chanced upon the # symbol, and used it for the first time in a tweet on August 23, 2007, “how do you feel about using # (pound) for groups. As in #barcamp [msg]?”
Chris Messina used the # symbol as an organizing tool for the Twitter community. Twitter did not have a way to support groups, and using the # symbol provided a way to categorize by topic, and indicate topicality. He only picked it because it already existed on mobile phone keypads, and was therefore readily available to use.
And with that, a symbol that started its journey with the Romans finally achieved greatness in social media as a hashtag. On a daily basis around 125 million hashtags are shared daily on Twitter.