Hashtag
A hashtag is a metadata tag that is prefaced by the hash symbol, #. On social media, hashtags are used on microblogging and photo-sharing services such as X (formerly Twitter) or Tumblr as a form of user-generated tagging that enables cross-referencing of content by topic or theme.[1] For example, a search within Instagram for the hashtag #bluesky returns all posts that have been tagged with that term. After the initial hash symbol, a hashtag may include letters, numerals, or underscores.[2]
For the group, see HashTag (group).The use of hashtags was first proposed by American blogger and product consultant Chris Messina in a 2007 tweet.[3][4] Messina made no attempt to patent the use because he felt that "they were born of the internet, and owned by no one".[5][6] Hashtags became entrenched in the culture of Twitter[7] and soon emerged across Instagram, Facebook, and YouTube.[8][9] In June 2014, hashtag was added to the Oxford English Dictionary as "a word or phrase with the symbol # in front of it, used on social media websites and apps so that you can search for all messages with the same subject".[10][11]