Includes historical hashtag list from the blog -- https://blog.twitter.com
On August 23, 2007 at 12:25pm, [Chris] Messina Tweeted "how do you feel about using # (pound) for groups. As in #barcamp [msg]?"
Social media platforms are just like any other social space -- restaurants, parks, bars and coffee shops, and meetings of all types. Sometimes, the southwest corner of a park is taken over by chess players of all ages and types; other times (or a few years or decades later) it might be the place for new parents to push their kids' strollers. The trendy restaurant of this year is sure to be replaced by another trending restaurant over time (maybe it's a new restaurant or maybe it's a new trend).
Some special cases jump off the merry-go-round of change as they do something so special that is remains away from the churning of social spaces. These social spaces last forever and ever...until they don't.