What is a hashtag?

A hashtag is a tool used in social media to tag and simplify searches for relevant terms. It involves prefacing a term with the hash symbol, allowing it to be entered into the website's search database.

The use of hashtags was popularized by the microblogging site Twitter and adopted by several other sites, such as Tumblr and Facebook. Hashtags are typically used within simple messages or blog posts as a broad means of labeling the content of the message. They may be used to join conversations involving trending topics, as they allow tagged messages to be easily found by searching the topic in the website's search engine.