Twitter defines hashtags as "a written with a # symbol—is used to index keywords or topics on Twitter".  A study conducted by Twitter shows that "Tweets with hashtags (the # symbol, immediately followed by the subject or keyword related to the Tweet) can increase engagement almost 100% (2x) for individuals and 50% (1.5x) for brands."

Using the right hashtags can not only boost your post's online visibility, but also increase chances of your audience being able to identify and engage with your Brand. When you add hashtags to your post, your content becomes more discoverable and lets people catch up on trending topics.

While it's great to add hashtags to your post, adding too many hashtags to your post can be noisy and overwhelming for your audience as this takes focus away from your main content.

In their best practices guide, Twitter recommends "using no more than 2 hashtags per Tweet".

There's more research pointing to the fact that "Tweets with one or 2 hashtags have 21% higher engagement than those with 3 or more hashtags". According to a study, posting more than two hashtags can reduce your audience engagement by 17 percent.

Clearly then, the best way to ensure your tweets get optimal engagement while also following twitter's recommendation is by including not more than two hashtags per tweet.

While it may be acceptable, and even beneficial to use more than two hashtags for each post you make on some of the other social networks, the same is not true for Twitter. For example, it might be a great idea to use the right keywords to caption your images on Instagram by adding multiple hashtags. This is because, on Instagram the main content that is, images or video, is clearly separated from the caption that contains these hashtags. So if you're planning to cross-post the same content to different channels, make sure to reduce the number of hashtags, if you do intend to post the content to Twitter too.

To learn more about how your business can use hashtags on Twitter, check out this handy guide on "The do's and don'ts of hashtags".