From humble origins as a simple number sign, the hashtag (once known as the pound sign) is now considered the symbol of the 21st century.
For many, however, it might be the most overused and obnoxious symbol ever invented. It may even be destroying the English language.
None of this has stopped Facebook from announcing this week that it will be using the metadata tag in its newsfeed.
The idea is to make Facebook better suited to public conversations and debates, much like Twitter.
The hashtags can be searched in order to find topics you're interested in, from #happiness to #nihilism.
"To date, there has not been a simple way to see the larger view of what's happening or what people are talking about," Facebook's Greg Lindley wrote on the company's blog.
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"To bring these conversations more to the forefront, we will be rolling out a series of features that surface some of the interesting discussions people are having about public events, people, and topics. As a first step, we are beginning to roll out hashtags on Facebook."
Users will still be able to limit who can see their hashtagged posts, though advertisers will clearly be interested in knowing what topics you post about. The hashtag will likely make that easier.
Given that many Facebook conversations are private or among a limited group of people, it is unclear if hashtags will have the same impact as they would on Twitter.
Needless to say, not everybody is happy about the change.