Buffer does a nice job of spelling out the invention of the twitter hashtag use.
The hashtag was first brought to Twitter on August 23, 2007 by Chris Messina. Before this, the hash (or pound) symbol had been used in various ways around the web, which helped Chris in developing his detailed suggestion for using hashtags on Twitter.
Chris took direction from similar uses of the hash symbol he’d already seen on other sites when designing the hashtag for Twitter.
It occurred to me that IRC presents a proven model for these needs with its foundation on channels, and so that’s what I’m generally going to call them.
Chris also wanted to find a way to incorporate hashtags into his current use of Twitter, so that SMS or IM clients could be used to interact with hashtags, and no web-based management would be required to set them up. He looked to a similar social network, Jaiku for a good example…
Will you be using hashtags more?