Hashtags make sense on Twitter. Since the social network’s model revolves around up-to-the-second news, users need a way to tag their posts so they won’t get lost.

But what about on Facebook? The platform supports hashtags in the same way as Twitter, but users do not use them as widely on Facebook as they do on Twitter, and (more recently) as they do on Instagram.

Since Facebook is fundamentally different from Twitter, the hashtag is bound to work differently as well. Hashtags function on Twitter the same way groups do on Facebook: they narrow down the scope of what an individual user sees from the whole social network to the one discourse of his interest. The fact that Facebook is a more private social network by nature drives the hashtag into irrelevance there. Since Facebook already has groups, pages, and preferred feeds to group like-minded people together, hashtags become just another superfluous grouping tool.

In addition, posts on Facebook with hashtags tend to get less exposure than posts that do not contain them. Whether it be because the hashtag has become an overexposed tool on social media or that Facebook users just are more wary of them than Twitter users, the numbers don’t lie. Hashtags drive engagement down on Facebook.

The bottom line is this. Hashtags serve a murky purpose on Facebook, and for your business, it is best to avoid them when writing your posts.