Twitter hashtags are so ingrained in Twitter now that I rarely second-guess them. They seem so much a part of the service, it’s as if Twitter shipped with them in its original version, even before it had vowels in the name.
But actually, Twitter’s version of the hashtag has a vibrant history which is really fascinating. Let’s take a look at the origins of the hashtag and how to use it best on Twitter.
The very ephemerality of hashtags is what makes them easy and compelling to use in a fast-moving communication medium like Twitter. – Chris Messina
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.
via The Buffer Blog.