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A sign suggesting the use of a #TimeToAct hashtag at a 2014 conference

A hashtag is a type of label or metadata tag used on social network and microblogging services which makes it easier for users to find messages with a specific theme or content. Users create and use hashtags by placing the hash character (or number sign) # in front of a word or unspaced phrase, either in the main text of a message or at the end. Searching for that hashtag will then present each message that has been tagged with it.

For example, on the photo-sharing service Instagram the hashtag #bluesky allows users to find images that have been tagged as containing the sky, and #cannes2014 is a popular tag for images from the 2014 Cannes Film Festival. Hashtags can be used to collect public opinion on events and ideas at the local, corporate, or world level. For example, searching Twitter for #worldcup2014 returns many tweets from individuals around the globe about the 2014 FIFA World Cup.

Hashtags have been used for social activism. The Twitter hashtags #notallmen and #yesallwomen were used to debate misogyny after the 2014 Isla Vista killings; while the #illridewithyou hashtag was created to tag messages of support for Australian Muslims using public transport after the 2014 Sydney hostage crisis.

Because of its widespread use, hashtag was added to the Oxford English Dictionary in June 2014.[1][2]

The term hashtag can also refer to the hash symbol itself when used in the context of a hashtag.[3]

Origin and use[edit]

The number sign was often used in information technology to highlight a special meaning. In 1970 for example, the number sign was used to denote immediate address mode in the assembly language of the PDP-11[4] when placed next to a symbol or a number. In 1978, Brian Kernighan and Dennis Ritchie used # in the C programming language for special keywords that had to be processed first by the C preprocessor.[5] Since before the invention of the hashtag, the number sign has been called the "hash symbol" in some countries outside of North America.[6][7]

The number sign then appeared and was used within IRC networks to label groups and topics.[8] Channels or topics that are available across an entire IRC network are prefixed with a hash symbol # (as opposed to those local to a server, which use an ampersand '&').[9]

The use of the number sign in IRC inspired[10] Chris Messina to propose a similar system to be used on Twitter to tag topics of interest on the microblogging network.[11] He posted the first hashtag on Twitter:

how do you feel about using # (pound) for groups. As in #barcamp [msg]?

— Chris Messina, ("factoryjoe"), August 23, 2007[12]

Internationally, the hashtag became a practice of writing style for Twitter posts during the 2009–2010 Iranian election protests, as both English- and Persian-language hashtags became useful for Twitter users inside and outside Iran.[13]

The first use of the term "hash tag" was in a blog post by Stowe Boyd, "Hash Tags = Twitter Groupings,"[14] on August 26, 2007, according to lexicographer Ben Zimmer, chair of the American Dialect Society's New Words Committee.

Beginning July 2, 2009,[citation needed] Twitter began to hyperlink all hashtags in tweets to Twitter search results for the hashtagged word (and for the standard spelling of commonly misspelled words). In 2010, Twitter introduced "Trending Topics" on the Twitter front page, displaying hashtags that are rapidly becoming popular. Twitter has an algorithm to tackle attempts to spam the trending list and ensure that hashtags trend naturally.[15]

In China, microblogs Sina Weibo and Tencent Weibo utilize a double-hashtag "#HashName#" format, since the lack of spacing between Chinese characters necessitates a closing tag. In contrast, when using Chinese characters (and orthographies with similar spacing conventions) on Twitter, users must insert spacing before and after the hashtagged element (e.g. '我 #爱 你' instead of '我#爱你')[16] or insert a zero-width non-joiner character before and after the hashtagged element, to retain a linguistically natural appearance, such as '我#爱你'.[17]


On microblogging or social networking sites, hashtags can be inserted anywhere within a sentence, either preceding it, following it as a postscript, or being included as a word within the sentence (e.g. "It is #sunny today").

The quantity of hashtags used in a post or tweet is just as important as the types of hashtags used. It is currently considered acceptable to tag a post once when contributing to a specific conversation. Two hashtags are considered acceptable when adding a location to the conversation. Three hashtags are seen by some as the "absolute maximum", and any contribution exceeding this risks “raising the ire of the community.”[18]

As well as frustrating other users, the misuse of hashtags can lead to account suspensions. Twitter warns that adding hashtags to unrelated tweets, or repeated use of the same hashtag without adding to a conversation, could cause an account to be filtered from search, or even suspended.[19][not in citation given]

Jimmy Fallon and Justin Timberlake performed a sketch parodying the often misused and misunderstood usage of hashtags on Late Night with Jimmy Fallon in September 2013.[20]


Search bar in the header of a social networking site, searching for most recent posts containing the hashtag "#science".

Hashtags are mostly used as unmoderated ad hoc discussion forums; any combination of characters led by a hash symbol is a hashtag, and any hashtag, if promoted by enough individuals, can "trend" and attract more individual users to discussion. On Twitter, when a hashtag becomes extremely popular, it will appear in the "Trending Topics" area of a user's homepage. The trending topics can be organized by geographic area or by all of Twitter. Hashtags are neither registered nor controlled by any one user or group of users, and neither can they be "retired" from public usage, meaning that any given hashtag can theoretically be used in perpetuity. They also do not contain any set definitions, meaning that a single hashtag can be used for any number of purposes as espoused by those who make use of them.

Hashtags intended for discussion of a particular event tend to use an obscure wording to avoid being caught up with generic conversations on similar subjects, such as a cake festival using "#cakefestival" rather than simply "#cake". However, this can also make it difficult for topics to become "trending topics" because people often use different spelling or words to refer to the same topic. In order for topics to trend, there has to be a consensus, whether silent or stated, that the hashtag refers to that specific topic.

Hashtags also function as beacons in order for users to find and "follow" (subscribe) or "list" (organize into public contact lists) other users of similar interest.

In recent years, broadcasters such as Channel 4 have employed the hashtag during the airing of programmes such as First Dates and The Undateables. Research has shown that audience numbers go up when the interactive element of tweeting while viewing something on TV occurs.

Hashtags can be used on the social network Instagram, by posting pictures and hashtagging it with its subject. As an example, a photo of oneself and a friend posted to the social network can be hashtagged #bffl or #friends. Instagram has banned certain hashtags, some because they are too generic, like #photography #iPhone #iphoneography, and therefore do not fulfill a purpose. They have also blocked hashtags that can be linked to illegal activities, such as drug use.[21] The ban against certain hashtags has a consequential role in the way that particular subaltern communities are built and maintained on Instagram. Despite Instagram’s content policies, users are finding creative ways of maintaining their practices and ultimately circumventing censorship.[22]

Hashtags are also used informally to express context around a given message, with no intent to actually categorize the message for later searching, sharing, or other reasons. This can help express humor, excitement, sadness or other contextual cues, for example "It's Monday!! #excited #sarcasm"

Other uses[edit]

The feature has been added to other, non-short-message-oriented services, such as the user comment systems on YouTube and Gawker Media; in the case of the latter, hashtags for blog comments and directly submitted comments are used to maintain a more constant rate of user activity even when paid employees are not logged into the website.[23][24] Real-time search aggregators such as the former Google Real-Time Search also support hashtags in syndicated posts, meaning that hashtags inserted into Twitter posts can be hyperlinked to incoming posts falling under that same hashtag; this has further enabled a view of the "river" of Twitter posts which can result from search terms or hashtags.[citation needed]


Broadcast media[edit]

The use of hashtags has also extended to television—a concept that began rising in prominence in 2010. Broadcasters may display a hashtag as an on-screen bug, encouraging viewers to participate in a backchannel of discussion via social media prior to, during, or after the program. Television commercials have also sometimes contained hashtags for similar purposes.[25] This is used as a means of promoting a Hashtag bugs appear on either corner of the screen, or they may appear at the end of an advertisement[26]

While personalities associated with broadcasts, such as hosts and correspondents, also promote their corporate or personal Twitter usernames in order to receive mentions and replies to posts, usage of related or "branded" hashtags alongside Twitter usernames (e.g., #edshow as well as @edshow) is increasingly encouraged as a microblogging style in order to "trend" the hashtag (and, hence, the discussion topic) in Twitter and other search engines. Broadcasters also make use of such a style in order to index select posts for live broadcast. Chloe Sladden, Twitter's director of media partnerships, identified two types of television-formatted usage of hashtags: hashtags which identify a series being broadcast (i.e. #SunnyFX) and instantaneous, "temporary" hashtags issued by television personalities to gauge topical responses from viewers during broadcasts.[27] Some have speculated that hashtags might take the place of (or co-exist with) the Nielsen television ratings system.[28]

The increased usage of hashtags as brand promotion devices has been compared to the promotion of branded "keywords" by AOL in the late 1990s and early 2000s, as such keywords were also promoted at the end of commercials and series episodes.[29]

Some hashtags became famous worldwide. For instance the slogan Je suis Charlie that was first used on Twitter as the hashtag #jesuischarlie and #iamcharlie and spread to the internet at large.


Since February 2013 there is a collaboration between the social networking site Twitter and American Express that makes it possible to buy discounted goods online by tweeting a special hashtag.[30] American Express members can sync their card with Twitter and use the offers by tweeting and look for a response in a tweet with the confirmation from American Express.[31]

Event promotion[edit]

Stencil graffiti promoting the hashtag #OccupyForRights

Organized real-world events have also made use of hashtags and ad hoc lists for discussion and promotion among participants. Hashtags are used as beacons by event participants in order to find each other on both Twitter and, in many cases, in real life during events.

Companies and advocacy organizations have taken advantage of hashtag-based discussions for promotion of their products, services or campaigns.

Political protests and campaigns in the early 2010s, such as #OccupyWallStreet and #LibyaFeb17, have been organized around hashtags or have made extensive usage of hashtags for the promotion of discussion.

Consumer complaints[edit]

Hashtags are often used by consumers on social media platforms in order to complain about the customer service experience with large companies. The term "bashtag" has been created to describe situations in which a corporate social media hashtag is used to criticise the company or to tell others about poor customer service. For example, in January 2012, McDonald's created the #McDStories hashtag so customers could share positive experiences about the restaurant chain. The marketing effort was cancelled after just two hours when McDonald's received numerous complaint tweets rather than the positive stories they were expecting.[32]

Sentiment analysis[edit]

The use of hashtags also reveals things about the sentiment an author attaches to a statement. This can range from the obvious, where a hashtag directly describes the state of mind, to the less obvious. For example, words in hashtags are the strongest predictor of whether or not a statement is sarcastic[33]—a difficult AI problem.[citation needed]

In popular culture[edit]

During the April 2011 Canadian party leader debate, then-leader of the New Democratic Party Jack Layton referred to Conservative Prime Minister Stephen Harper's crime policies as "a hashtag fail" (presumably "#fail").[34][35]

The term "hashtag rap", coined by Kanye West,[36] was developed in the 2010s to describe a style of rapping which, according to Rizoh of Houston Press, uses "three main ingredients: a metaphor, a pause, and a one-word punch line, often placed at the end of a rhyme".[37] Rappers Nicki Minaj, Big Sean, Drake and Lil Wayne are credited with the popularization of hashtag rap, while the style has been criticized by Ludacris, The Lonely Island[38] and various music writers.[39]

On September 13, 2013, a hashtag, #TwitterIPO, appeared in the headline of a New York Times front page article regarding Twitter's initial public offering.[40]

"Hashtag heel" is a moniker used by WWE wrestler Dolph Ziggler.

Bird's Eye foods released in 2014 a shaped mashed potato food that included forms of @-symbols and hashtags, called "Mashtags".[41]

In May 2014, Twitter users began using the hashtag #YesAllWomen to raise awareness about personal experiences of sexism and violence against women.[42]

In September 2014, in response to the "blame the victim" public reactions to videotaped footage of NFL player Ray Rice assaulting his then-fiancée Janay Palmer in the elevator of an Atlantic City casino, Beverly Gooden shared on Twitter her own story of domestic abuse, using the hashtag #WhyIStayed, and encouraged others to share theirs.[43][44]


In 2010, Twitter introduced "hashflags" during the 2010 World Cup in South Africa.[45] They reintroduced the feature on June 10, 2014, in time for the 2014 World Cup in Brazil,[46][47] and then again on April 10, 2015, with UK political party logos for the 2015 UK General Election.[48] When a user tweets a hashtag consisting of the three letter country code of any of the 32 countries represented in the tournament, Twitter automatically embeds a flag emoticon for that country.

In July 2012, Twitter adapted the hashtag style to make company ticker symbols preceded by the dollar sign clickable (as in $AAPL), a method that Twitter dubbed the "cashtag".[49][50] This is intended to allow users to search posts discussing companies and their stocks.

In August 2012, British journalist Tom Meltzer reported in The Guardian about a new hand gesture that mimicked the hashtag, sometimes called the "finger hashtag", in which both hands form a peace sign, and then the fingers are crossed to form the symbol of a hashtag.[51] The emerging gesture was reported about in Wired by Nimrod Kamer,[52] and during 2013 it was seen on TV used by Jimmy Fallon, and on The Colbert Report among other places.[53]


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