A hashtag is a word or phrase preceded by a hash symbol (#) and used to identify messages on a specific topic. The hashtag is used to categorise messages and make it easier for users to find content that is relevant to them.

Hashtags are commonly used on social media platforms such as Twitter, Instagram and Facebook. To use a hashtag, users simply add it to their post or tweet, preceded by the hash symbol. For example, if a user wants to share a post about dogs, they can include the hashtag #Hounds in their post. Other users interested in dogs could then search for the hashtag #dogs to see all posts tagged with that hashtag.

Hashtags can be used to facilitate discussion on a particular topic and can help create a sense of community among users who are interested in the same things.