The use of hashtags in your Twitter messages is fundamental to your Twitter experience. This is how people outside your followers get to know you and how you filter the vast amount of tweets. A hashtag is used to mark a topic in Twitter.
For example, if you’re an Australian Open Tennis fan and you’d like to join in the conversation, you can type in #ausopen, the hashtag for all things Australian Open related. From here you’ll see what people are talking about then you can chime in by adding #ausopen to your tweet or reply directly to someone’s tweet.
If you’re trying to engage an audience relating to your business, is worth research popular and relevant hashtags. I use a website called hashtagify.me which is easy to use.
Hashtags are also used in Instagram but that’s another story for another blog.