Hashtags are a form of metadata used to cross-reference content by adding the hash symbol (#) as a prefix to specific segments of text. A search for a specific hashtag will return all the public posts that included it. Widespread use of a hashtag on social media can be indicative that the topic it refers to is trending, though this also means that some users will attempt to draw attention to a topic by spamming its hashtag to make it appear more popular than it actually is.
