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Chris Messina, the inventor of the hashtag Chris Messina - South by Southwest 2010 (1).jpg
Chris Messina, the inventor of the hashtag

A hashtag is a metadata tag that is prefaced by the hash symbol, #. Hashtags are widely used on microblogging and photo-sharing services such as Twitter and Instagram as a form of user-generated tagging that enables cross-referencing of content sharing a subject or theme. [1] For example, a search within Instagram for the hashtag #bluesky returns all posts that have been tagged with that hashtag. After the initial hash symbol, a hashtag may include letters, digits, and underscores. [2]


The use of hashtags was first proposed by Chris Messina in a 2007 tweet. [3] [4] Messina made no attempt to patent the use because he felt "they were born of the internet, and owned by no one". [5] [6] Twitter initially decried hashtags as a "thing for nerds," [7] but by the end of the decade hashtags were entrenched in the culture of the platform and were emerging across Instagram, Facebook, Reddit, and YouTube. [8] In June 2014, 'hashtag' was added to the Oxford English Dictionary . [9] [10]

Origin and acceptance

The number sign or hash symbol, '#', has long been used in information technology to highlight specific pieces of text. In 1970, the number sign was used to denote immediate address mode in the assembly language of the PDP-11 [11] when placed next to a symbol or a number, and in 1978, Brian Kernighan and Dennis Ritchie used '#' in the C programming language to indicate special keywords that the C preprocessor had to process first. [12] The pound sign was adopted for use within IRC (Internet Relay Chat) networks circa 1988 to label groups and topics. [13] 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 '&'). [14]

The use of the pound sign in IRC inspired [15] Chris Messina to propose a similar system on Twitter to tag topics of interest on the microblogging network. [16] 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 [3]

According to Messina, he suggested use of the hashtag to make it easy for lay users without specialized knowledge of search protocols to find specific relevant content. Therefore, the hashtag "was created organically by Twitter users as a way to categorize messages." [17]

The first published use of the term "hash tag" was in a blog post by Stowe Boyd, "Hash Tags = Twitter Groupings," [18] on August 26, 2007, according to lexicographer Ben Zimmer, chair of the American Dialect Society's New Words Committee.

A sign with a #TimeToAct hashtag at a 2014 conference Global Summit to End Sexual Violence in Conflict (14203190979).jpg
A sign with a #TimeToAct hashtag at a 2014 conference

Messina's suggestion to use the hashtag was not immediately adopted by Twitter, but the convention gained poplular acceptance when hashtags were widely used in tweets relating to the 2007 San Diego forest fires in Southern California. [19] [20] The hashtag gained international acceptance during the 2009–2010 Iranian election protests; Twitter users used both English- and Persian-language hashtags in communications during the events. [21]

Hashtags have since played critical roles in recent social movements such as #jesuischarlie, #BLM, [22] and #MeToo. [23] [24]

Beginning July 2, 2009, [25] 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, and the significance of trending hashtags as become so great that the company makes significant efforts to foil attempts to spam the trending list. [26] During the 2010 World Cup, Twitter explicitly encouraged the use of hashtags with the temporary deployment of "hashflags", which replaced hashtags of three-letter country codes with their respective national flags. [27]

Other platforms such as YouTube and Gawker Media followed in officially supporting hashtags, [28] and real-time search aggregators such as Google Real-Time Search began supporting hashtags.


A hashtag must begin with a hash character followed by other characters, and is terminated by a space or end of message. Some platforms may require the # to be preceded with a space. Most or all platforms that support hashtags permit the inclusion of letters (without diacritics), numerals, and underscores. [2] Other characters may be supported on a platform-by-platform basis. Some characters, such as & are generally not supported as they may already serve other search functions. [29] Hashtags are not case sensitive (a search for "#hashtag" will match "#HashTag" as well), but the use of embedded capitals (i.e., CamelCase) increases legibility and improves accessibility.

Languages that do not use word dividers handle hashtags differently. In China, microblogs Sina Weibo and Tencent Weibo use a double-hashtag-delimited #HashName# format, since the lack of spacing between Chinese characters necessitates a closing tag. Twitter uses a different syntax for Chinese characters and orthographies with similar spacing conventions: the hashtag contains unspaced characters, separated from preceding and following text by spaces (e.g., '我 #爱 你' instead of '我#爱你') [30] or by zero-width non-joiner characters before and after the hashtagged element, to retain a linguistically natural appearance (displaying as unspaced '我‌#爱‌你', but with invisible non-joiners delimiting the hashtag). [31]

Etiquette and regulation

Some communities may limit, officially or unofficially, the number of hastags permitted on a single post. [32]

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 can filter an account from search results, or suspend the account. [33]

Individual platforms may deactivate certain hashtags either for being too generic to be useful, such as #photography on Instagram, or due to their use to facilitate illegal activities. [34] [35]

Alternate formats

In 2009, StockTwits began using ticker symbols preceded by the dollar sign (e.g., $XRX). [36] [37] In July 2012, Twitter began supporting the tag convention and dubbed it the "cashtag". [38] [39] The convention has extended to national currencies, and Cash App has implemented the cashtag to mark usernames.


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

Hashtags are particularly useful in unmoderated forums that lack a formal ontological organization. Hashtags help users find content similar interest. Hashtags are neither registered nor controlled by any one user or group of users. They do not contain any set definitions, meaning that a single hashtag can be used for any number of purposes, and that the widely accepted meaning of a hashtag can change with time.

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. For topics to trend, there must be a consensus, whether silent or stated, that the hashtag refers to that specific topic.

Hashtags may be used informally to express context around a given message, with no intent to categorize the message for later searching, sharing, or other reasons. Hashtags may thus serve as a reflexive meta-commentary. [40]

This can help express contextual cues or offer more depth to the information or message that appears with the hashtag. "My arms are getting darker by the minute. #toomuchfaketan". Another function of the hashtag can be used to express personal feelings and emotions. For example, with "It's Monday!! #excited #sarcasm" in which the adjectives are directly indicating the emotions of the speaker. [41]

Verbal use of the word 'hashtag' is sometimes used in informal conversations. [42] Use may be humorous, such as "I'm hashtag confused!" [41] By August 2012, use of a hand gesture, sometimes called the "finger hashtag", in which the index and middle finger both hands are extended and arranged perpendicularly to form the hash, was widely documented. [43] [44]

Co-optation by other industries

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

Hashtags began appearing prominently in television broadcasts in the early 2010s. 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 sometimes contained hashtags for similar purposes. [45] Hashtag bugs appear on either corner of the screen, or they may appear at the end of an advertisement. [46]

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 television commercials and series episodes. [47]

Stencil graffiti promoting the hashtag #OccupyForRights Occupy for Rights.JPG
Stencil graffiti promoting the hashtag #OccupyForRights

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

Since the 2012–13 season, the NBA has allowed fans to vote players in as All-Star Game starters on Twitter and Facebook using #NBAVOTE. [48]

Non-commercial use

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. Hashtags have also been used to promote official events; the Finnish Ministry of Foreign Affairs officially titled the 2018 Russia–United States summit as the "#HELSINKI2018 Meeting". [49]

Hashtags have been used to gather customer criticism of large companies. In January 2012, McDonald's created the #McDStories hashtag so that customers could share positive experiences about the restaurant chain, but the marketing effort was cancelled after two hours when critical tweets outnumbered praising ones. [50]

Sentiment analysis

The use of hashtags also reveals what feelings or 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 [51] —a difficult AI problem. [52]


An analysis of eight studies that examined the use of hashtags in K–12 classrooms indicated that use of hashtags empower students to voice their ideas and help them with self-organization, emerging knowledge, and understanding space beyond place.[ clarification needed ] [53]

Two young men displaying the hashtag hand gesture Armandas.jpg
Two young men displaying the hashtag hand gesture

During the April 2011 Canadian party leader debate, Jack Layton, then-leader of the New Democratic Party, referred to Conservative Prime Minister Stephen Harper's crime policies as "a[ sic ] hashtag fail" (presumably #fail). [54] [55]

In 2010 Kanye West used the term "hashtag rap" to describe a style of rapping that, according to Rizoh of the Houston Press, uses "a metaphor, a pause, and a one-word punch line, often placed at the end of a rhyme". [56] [57] 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, [58] and various music writers. [59]

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. [60] [61]

In 2014 Bird's Eye foods released "Mashtags", a mashed potato product with pieces shaped either like @ or #. [62]

In 2019, the British Ornithological Union included as hash character in the design of its new Janet Kear Union Medal, to represent "science communication and social media". [63]

See also

Related Research Articles

The symbol # is known as the number sign, hash, or, in North American usage, pound sign. The symbol has historically been used for a wide range of purposes including the designation of an ordinal number and as a ligatured abbreviation for pounds avoirdupois – having been derived from the now-rare .

Tag (metadata) Keyword assigned to information

In information systems, a tag is a keyword or term assigned to a piece of information. This kind of metadata helps describe an item and allows it to be found again by browsing or searching. Tags are generally chosen informally and personally by the item's creator or by its viewer, depending on the system, although they may also be chosen from a controlled vocabulary.

Chris Messina (open-source advocate) American blogger, product consultant and speaker (born 1981)

Christopher Reaves Messina is an American blogger, product consultant and speaker who is the inventor of the hashtag as it is currently used on social media platforms. In a 2007 tweet, Messina proposed vertical/associational grouping of messages, trends, and events on Twitter by the means of hashtags. The hashtag was intended to be a type of metadata tag that allowed users to apply dynamic, user-generated tagging, which made it possible for others to easily find messages with a specific theme or content. It allowed easy, informal markup of folksonomy without need of any formal taxonomy or markup language. Hashtags have since been referred to as the "eavesdroppers", "wormholes", "time-machines", and "veins" of the Internet.

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

Social search is a behavior of retrieving and searching on a social searching engine that mainly searches user-generated content such as news, videos and images related search queries on social media like Facebook, LinkedIn, Twitter, Instagram and Flickr. It is an enhanced version of web search that combines traditional algorithms. The idea behind social search is that instead of ranking search results purely based on semantic relevance between a query and the results, a social search system also takes into account social relationships between the results and the searcher. The social relationships could be in various forms. For example, in LinkedIn people search engine, the social relationships include social connections between searcher and each result, whether or not they are in the same industries, work for the same companies, belong the same social groups, and go the same schools, etc.

Twitter American microblogging service

Twitter is an American microblogging and social networking service on which users post and interact with messages known as "tweets". Registered users can post, like and retweet tweets, but unregistered users can only read them. Users access Twitter through its website interface or its mobile-device application software ("app"), though the service could also be accessed via SMS before April 2020. Twitter, Inc. is based in San Francisco, California, and has more than 25 offices around the world. Tweets were originally restricted to 140 characters, but was doubled to 280 for non-CJK languages in November 2017. Audio and video tweets remain limited to 140 seconds for most accounts.

Social network advertising, also social media targeting, is a group of terms that are used to describe forms of online advertising that focus on social networking services. One of the major benefits of this type of advertising is that advertisers can take advantage of the users' demographic information and target their ads appropriately.

Social media marketing is the use of social media platforms and websites to promote a product or service. Although the terms e-marketing and digital marketing are still dominant in academia, social media marketing is becoming more popular for both practitioners and researchers. Most social media platforms have built-in data analytics tools, enabling companies to track the progress, success, and engagement of ad campaigns. Companies address a range of stakeholders through social media marketing, including current and potential customers, current and potential employees, journalists, bloggers, and the general public. On a strategic level, social media marketing includes the management of a marketing campaign, governance, setting the scope and the establishment of a firm's desired social media "culture" and "tone."

Twitter usage

Since the launch of Twitter on July 15, 2006, there have been many notable uses for the service, in a variety of environments.

Sina Weibo Chinese microblogging website

Sina Weibo (新浪微博) is a Chinese microblogging (weibo) website. Launched by Sina Corporation on 14 August 2009, it is one of the biggest social media platforms in China, with over 445 million monthly active users as of Q3 2018. The platform has been a huge financial success, with surging stocks, lucrative advertising sales and high revenue and total earnings per quarter. At the start of 2018, it surpassed the US$30 billion market valuation mark for the first time.

Reblogging is the mechanism in blogging which allows users to repost the content of another user's post with an indication that the source of the post is another user.

Instagram Online photo-sharing and social networking service

Instagram is an American photo and video sharing social networking service created by Kevin Systrom and Mike Krieger. In April 2012, Facebook acquired the service for approximately US$1 billion in cash and stock. The app allows users to upload media that can be edited with filters and organized by hashtags and geographical tagging. Posts can be shared publicly or with pre-approved followers. Users can browse other users' content by tags and locations and view trending content. Users can like photos and follow other users to add their content to a personal feed.

Shadow banning, also called stealth banning, ghost banning or comment ghosting, is the practice of blocking or partially blocking a user or their content from an online community so that it will not be readily apparent to the user that they have been banned. For instance, shadow banned comments posted to a blog or media website will not be visible to other persons accessing that site from their computers.

Social media and television

Social media and television broadcasting have a number of connections and interrelationships. In the 2010s, social media technologies and websites allow for television shows to be accessed online on a range of desktop and mobile computer devices, smartphones and smart TVs. As well, online users can use social media websites to share digital video clips or excerpts from TV shows with fellow fans or even share an entire show online. Many social media websites enable users to post online comments on the programs—both negative and positive—in a variety of ways. Viewers can actively participate while watching a TV program by posting comments online, and have their interactions viewed and responded to in real time by other viewers. Technologies such as smartphones, tablets, and laptop computers allow viewers to watch downloaded digital files of TV shows or "stream" digital files of TV shows on a range of devices, both in the home and while on the go. In the 2010s, some television producers and broadcasters are encouraging active social media participation by viewers by posting "hashtags" on the TV screen during shows; these hashtags enable viewers to post online comments about the show, which may either be read by other social media users, or even, in some cases, displayed on the screen.

The term twitter bomb or tweet bomb refers to posting numerous Tweets with the same hashtags and other similar content, including @messages, from multiple accounts, with the goal of advertising a certain meme, usually by filling people's Tweet feeds with the same message, and making it a "trending topic" on Twitter. This may be done by individual users, fake accounts, or both.

Networked feminism is a phenomenon that can be described as the online mobilization and coordination of feminists in response to perceived sexist, misogynistic, racist, and other discriminatory acts against minority groups. This phenomenon covers all possible definitions of what feminist movements may entail, as there have been multiple waves of feminist movements and there is no central authority to control what the term "feminism" claims to be. While one may hold a different opinion from another on the definition of "feminism", all those who believe in these movements and ideologies share the same goal of dismantling the current patriarchal social structure, where men hold primary power and higher social privileges above all others. Networked feminism is not spearheaded by one singular women's group. Rather, it is the manifestation of feminists' ability to leverage the internet to make traditionally unrepresented voices and viewpoints heard. Networked feminism occurs when social network sites such as Facebook, Twitter and Tumblr are used as a catalyst in the promotion of feminist equality and in response to sexism. Users of these social media websites promote the advancement of feminism using tools such as viral Facebook groups and hashtags. These tools are used to push gender equality and call attention to those promoting anything otherwise. Online feminist work is becoming a new engine of contemporary feminism. With the possibility of connecting and communicating all around the world through the Internet, no other form of activism in history has brought together and empowered so many people to take action on a singular issue.

Black Twitter is a community largely consisting of African American users on the social network Twitter focused on issues of interest to the black community, particularly in the United States. Feminista Jones described it in Salon as "a collective of active, primarily African-American Twitter users who have created a virtual community ... [and are] proving adept at bringing about a wide range of sociopolitical changes." A similar Black Twitter community grew in South Africa in the early 2010s. Although Black Twitter has a strong Black American user base, other people and groups are able to be a part of this social media circle through commonalities in shared experiences and reactions to such online. Calling out cultural appropriation was a chief focus of the space in the early 2010s.

Flutrack is a system that detects influenza symptoms by processing and displaying influenza related Twitter messages. Flutrack platform gathers and visualizes tweets every 20 minutes in real time. This open platform and its API allow users and developers to extend this project and take influenza detection to higher levels. The platform could work not only with Twitter but with any data provider.

Hashtag activism is a term coined by media outlets which refers to the use of Twitter's hashtags for Internet activism. The term can also be used to refer to the act of showing support for a cause through a like, share, etc. on any social media platform, such as Facebook or Twitter. The point of hashtag activism is arguably to share certain issues with one's friends and followers in the hopes that they will also share the same information. This leads to a widespread discussion and allows for change to occur. However, hashtags have also been used to debate and make people aware of social and political issues. They can be seen as a way to help or start a revolution by increasing the number of supporters from across the world who have not been in contact with the issue. It allows people to discuss and comment around one hashtag. Hashtag activism is a way to expand the usage of communication and make it democratic in a way that everyone has a way to express their opinions. Especially it provides an important platform for historically disenfranchised populations, enabling them to communicate, mobilize and advocate on topics less visible in mainstream media.

Social profiling is the process of constructing a user's profile using his or her social data. In general, profiling refers to the data science process of generating a person's profile with computerized algorithms and technology. There are various platforms for sharing this information with the proliferation of growing popular social networks, including but not limited to LinkedIn, Google+, Facebook and Twitter.

Twitter trends

On Twitter, a word, phrase, or topic that is mentioned at a greater rate than others is said to be a "trending topic" or simply a "trend". Trending topics become popular either through a concerted effort by users or because of an event that prompts people to talk about a specific topic. These topics help Twitter and their users to understand what is happening in the world and what people's opinions are about it.


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