Those who do search engine optimization for a living contend that the hashtag is not all that useful, since few people actually use them to search for the content they want.
But that doesn’t mean they aren’t useful bits of language. Rather than for search, hashtaggers use them to highlight important words or ideas and to mark affiliation with or commentary on social movements.
Witness the #MeToo movement or #BlackLivesMatter to see how this works: as we scan our feeds on Facebook or Twitter, these tags stand out, draw our attention to the words with which they are coupled.
So even if they don’t enhance automated search, hashtags significantly enhance the more mundane, and much more common, human search we do as we scroll through social media.
Hashtags also act as summaries of social media content, an important verbal feature when success lies in retweets and likes, often from readers whose attention is split many ways.
But we also use hashtags rhetorically, creating tension between our post’s content and the hashtags we invoke, for example by calling out #UniteTheRight as our content harangues them.
Going against the flow toward quicker and shorter forms of expression, the hashtag is additive, ironically speeding how we read by contextualizing what we read, allowing us to pick out what’s significant and scroll on past the rest.
But this also lets individuals regain the promise of online communication: attention from others that only broadcast media once enjoyed.