
A hashtag is a
metadata tag that is prefaced by the
hash
Hash, hashes, hash mark, or hashing may refer to:
Substances
* Hash (food), a coarse mixture of ingredients
* Hash, a nickname for hashish, a cannabis product
Hash mark
*Hash mark (sports), a marking on hockey rinks and gridiron football field ...
(also known as pound or octothorpe) sign, ''#''. On
social media
Social media are interactive media technologies that facilitate the creation and sharing of information, ideas, interests, and other forms of expression through virtual communities and networks. While challenges to the definition of ''social me ...
, hashtags are used on
microblogging and
photo-sharing services such as
Twitter
Twitter is an online social media and social networking service owned and operated by American company Twitter, Inc., on which users post and interact with 280-character-long messages known as "tweets". Registered users can post, like, and ...
or
Instagram
Instagram is a photo and video sharing social networking service owned by American company Meta Platforms. The app allows users to upload media that can be edited with filters and organized by hashtags and geographical tagging. Posts can ...
as a form of
user-generated
User-generated content (UGC), alternatively known as user-created content (UCC), is any form of content, such as images, videos, text, testimonials, and audio, that has been posted by users on online platforms such as social media, discussion f ...
tagging that enables
cross-referencing of content by topic or theme. 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.
The use of hashtags was first proposed by American
blogger and product consultant
Chris Messina in a 2007 tweet.
Messina made no attempt to patent the use because he felt that "they were born of the internet, and owned by no one". Hashtags became entrenched in the culture of Twitter and soon emerged across Instagram, Facebook, and YouTube. In June 2014, ''hashtag'' was added to the ''
Oxford English Dictionary
The ''Oxford English Dictionary'' (''OED'') is the first and foundational historical dictionary of the English language, published by Oxford University Press (OUP). It traces the historical development of the English language, providing a com ...
'' 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".
Origin and acceptance

The
number sign or hash symbol, ''#'', has long been used in
information technology
Information technology (IT) is the use of computers to create, process, store, retrieve, and exchange all kinds of data . and information. IT forms part of information and communications technology (ICT). An information technology system ...
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
The PDP-11 is a series of 16-bit minicomputers sold by Digital Equipment Corporation (DEC) from 1970 into the 1990s, one of a set of products in the Programmed Data Processor (PDP) series. In total, around 600,000 PDP-11s of all models were so ...
when placed next to a symbol or a number, and around 1973,'#' was introduced in the
C programming language
''The C Programming Language'' (sometimes termed ''K&R'', after its authors' initials) is a computer programming book written by Brian Kernighan and Dennis Ritchie, the latter of whom originally designed and implemented the language, as well as ...
to indicate special keywords that the
C preprocessor had to process first. The pound sign was adopted for use within IRC (
Internet Relay Chat
Internet Relay Chat (IRC) is a text-based chat system for instant messaging. IRC is designed for group communication in discussion forums, called '' channels'', but also allows one-on-one communication via private messages as well as chat a ...
) networks around 1988 to label groups and topics. 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
The ampersand, also known as the and sign, is the logogram , representing the conjunction "and". It originated as a ligature of the letters ''et''—Latin for "and".
Etymology
Traditionally in English, when spelling aloud, any letter tha ...
'&').
The use of the pound sign in IRC inspired
Chris Messina to propose a similar system on Twitter to tag topics of interest on the
microblogging network. He posted the first hashtag on Twitter:
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".
The first published use of the term "hash tag" was in a blog post "Hash Tags = Twitter Groupings" by Stowe Boyd, on August 26, 2007, according to
lexicographer
Lexicography is the study of lexicons, and is divided into two separate academic disciplines. It is the art of compiling dictionaries.
* Practical lexicography is the art or craft of compiling, writing and editing dictionaries.
* Theoretica ...
Ben Zimmer, chair of the
American Dialect Society's New Words Committee.

Messina's suggestion to use the hashtag was not immediately adopted by Twitter, but the convention gained popular acceptance when hashtags were used in tweets relating to the
2007 San Diego forest fires in Southern California.
The hashtag gained international acceptance during the
2009–2010 Iranian election protests
After incumbent president Mahmoud Ahmadinejad declared victory in the 2009 Iranian presidential election, protests broke out in major cities across Iran in support of opposition candidates Mir-Hossein Mousavi and Mehdi Karroubi. The protests con ...
; Twitter users used both English- and
Persian-language hashtags in communications during the events.
Hashtags have since played critical roles in recent
social movements
A social movement is a loosely organized effort by a large group of people to achieve a particular goal, typically a social or political
Politics (from , ) is the set of activities that are associated with making decisions in groups, or ...
such as
#jesuischarlie,
#BLM, and
#MeToo.
Beginning July 2, 2009, 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 has become so great that the company makes significant efforts to foil attempts to
spam the trending list. 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.
Other platforms such as
YouTube
YouTube is a global online video sharing and social media platform headquartered in San Bruno, California. It was launched on February 14, 2005, by Steve Chen, Chad Hurley, and Jawed Karim. It is owned by Google, and is the second most ...
and
Gawker Media
Gawker Media LLC (formerly Blogwire, Inc. and Gawker Media, Inc.) was an American online media company and blog network. It was founded by Nick Denton in October 2003 as Blogwire, and was based in New York City. Incorporated in the Cayman Is ...
followed in officially supporting hashtags, and real-time search aggregators such as
Google Real-Time Search
Google Search (also known simply as Google) is a search engine provided by Google. Handling more than 3.5 billion searches per day, it has a 92% share of the global search engine market. It is also the List of most visited websites, most-visi ...
began supporting hashtags.
Format
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. 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. 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 divider
In punctuation, a word divider is a glyph that separates written words. In languages which use the Latin, Cyrillic, and Arabic alphabets, as well as other scripts of Europe and West Asia, the word divider is a blank space, or ''whitespace''. ...
s 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
Chinese characters () are logograms developed for the writing of Chinese. In addition, they have been adapted to write other East Asian languages, and remain a key component of the Japanese writing system where they are known as '' kan ...
necessitates a closing tag.
Twitter
Twitter is an online social media and social networking service owned and operated by American company Twitter, Inc., on which users post and interact with 280-character-long messages known as "tweets". Registered users can post, like, and ...
uses a different syntax for Chinese characters and
orthographies
An orthography is a set of conventions for writing
Writing is a medium of human communication which involves the representation of a language through a system of physically Epigraphy, inscribed, Printing press, mechanically transferred, o ...
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') 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).
Etiquette and regulation
Some communities may limit, officially or unofficially, the number of hashtags permitted on a single post.
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.
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.
Alternate formats
In 2009,
StockTwits
StockTwits is a social media platform designed for sharing ideas between investors, traders, and entrepreneurs. The company was co-founded by Howard Lindzon and Soren Macbeth in 2009. The company received the first Shorty Award in the 2008 fina ...
began using
ticker symbols preceded by the
dollar sign
The dollar sign, also known as peso sign, is a symbol consisting of a capital " S" crossed with one or two vertical strokes ($ or ), used to indicate the unit of various currencies around the world, including most currencies denominated " ...
(e.g.,
$XRX).
In July 2012, Twitter began supporting the tag convention and dubbed it the "cashtag". The convention has extended to national currencies, and
Cash App
Cash App (formerly Square Cash) is a mobile payment service available in the United States and the United Kingdom that allows users to transfer money to one another (for a 1.5% fee for immediate transfer) using a mobile phone app. In September 2 ...
has implemented the cashtag to mark usernames.
Function

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 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.
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.
Verbal use of the word ''hashtag'' is sometimes used in informal conversations.
Use may be humorous, such as "I'm hashtag confused!"
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 documented.
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.
In the early 2010s, some
television
Television, sometimes shortened to TV, is a telecommunication Media (communication), medium for transmitting moving images and sound. The term can refer to a television set, or the medium of Transmission (telecommunications), television tra ...
broadcasters began to employ hashtags related to programs in
digital on-screen graphics, to encourage 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.
The increased usage of hashtags as brand promotion devices has been compared to the promotion of branded "
keywords
Keyword may refer to:
Computing
* Keyword (Internet search), a word or phrase typically used by bloggers or online content creator to rank a web page on a particular topic
* Index term, a term used as a keyword to documents in an information syste ...
" by
AOL in the late 1990s and early 2000s, as such keywords were also promoted at the end of television commercials and series episodes.
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.
Hashtag-centered biomedical Twitter campaigns have shown to increase the reach, promotion, and visibility of healthcare-related open innovation platforms.
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
The Ministry for Foreign Affairs (MFA) is a ministry in the Finnish Government and is responsible for preparing and implementing the government's foreign policy.
Organisation
The ministry in 2017 has a total budget of 1.079 billion euros, of ...
officially titled the
2018 Russia–United States summit
Eighteen or 18 may refer to:
* 18 (number), the natural number following 17 and preceding 19
* one of the years 18 BC, AD 18, 1918, 2018
Film, television and entertainment
* ''18'' (film), a 1993 Taiwanese experimental film based on the short s ...
as the "#HELSINKI2018 Meeting".
Hashtags have been used to gather customer criticism of large companies. In January 2012,
McDonald's
McDonald's Corporation is an American multinational fast food
Fast food is a type of mass-produced food designed for commercial resale, with a strong priority placed on speed of service. It is a commercial term, limited to food sold ...
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.
Hashtags have also been initiated by individuals to show support and criticism for political leaders during times of controversy. In August 2021,
Joe Biden was criticised for the way the nation dealt with
the collapse of Afghanistan's capital city of Kabul to the
Taliban
The Taliban (; ps, طالبان, ṭālibān, lit=students or 'seekers'), which also refers to itself by its state name, the Islamic Emirate of Afghanistan, is a Deobandi Islamic fundamentalist, militant Islamist, jihadist, and Pas ...
. As a result, the hashtag #WhereIsBiden began trending on Twitter. On the other hand, those standing in solidarity with the president tweeted #IStandWithBiden which started trending with almost 50,000 tweets.

In 2017, the
#MeToo hashtag became viral in response to the sexual harassment accusations against
Harvey Weinstein. The use of this hashtag can be considered part of
hashtag activism, spreading awareness across eighty-five different countries with more than seventeen million Tweets using the hashtag #MeToo. This hashtag was not only used to spread awareness of accusations regarding Harvey Weinstein but allowed different women to share their experiences of
sexual violence
Sexual violence is any sexual act or attempt to obtain a sexual act by violence or coercion, act to traffic a person, or act directed against a person's sexuality, regardless of the relationship to the victim.World Health Organization., Worl ...
. Using this hashtag birthed multiple different hashtags in connection to #MeToo to encourage more women to share their stories, resulting in further spread of the phenomenon of hashtag activism. The use of hashtags, especially, in this case, allowed for better and easier access to search for content related to this social media movement.
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—a difficult
AI problem.
Professional development and education
Hashtags play an important role for employees and students in professional fields and education. In industry, individuals' engagement with a hashtags can provide opportunities for them develop and gain some professional knowledge in their fields.
In education, research on language teachers who engaged in the #MFLtwitterati hashtag demonstrates the uses of hashtags for creating community and sharing teaching resources. The majority of participants reported positive impact on their teaching strategies as inspired by many ideas shared by different individuals in the Hashtag.
Emerging research in communication and learning demonstrates how hashtag practices influence the teaching and development of students. An analysis of eight studies examined the use of hashtags in K–12 classrooms and found significant results. These results indicated that hashtags assisted students in voicing their opinions. In addition, hashtags also helped students understand self-organisation and the concept of space beyond place. Related research demonstrated how high school students engagement with hashtag communication practices allowed them to develop story telling skills and cultural awareness.
For young people at risk of poverty and social exclusion during the
COVID-19 pandemic
The COVID-19 pandemic, also known as the coronavirus pandemic, is an ongoing global pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The novel virus was first identified ...
,
Instagram
Instagram is a photo and video sharing social networking service owned by American company Meta Platforms. The app allows users to upload media that can be edited with filters and organized by hashtags and geographical tagging. Posts can ...
hashtags were shown in a 2022 article to foster scientific education and promote remote learning.
In popular culture

During the
April 2011 Canadian party leader debate,
Jack Layton, then-leader of the
New Democratic Party
The New Democratic Party (NDP; french: Nouveau Parti démocratique, NPD) is a federal political party in Canada. Widely described as social democratic,The party is widely described as social democratic:
*
*
*
*
*
*
*
*
*
*
*
* ...
, referred to
Conservative
Conservatism is a cultural, social, and political philosophy that seeks to promote and to preserve traditional institutions, practices, and values. The central tenets of conservatism may vary in relation to the culture and civilization in ...
Prime Minister
Stephen Harper
Stephen Joseph Harper (born April 30, 1959) is a Canadian politician who served as the 22nd prime minister of Canada from 2006 to 2015. Harper is the first and only prime minister to come from the modern-day Conservative Party of Canada, ...
's crime policies as " hashtag fail" (presumably #fail).
In 2010
Kanye West
Ye ( ; born Kanye Omari West ; June 8, 1977) is an American rapper, singer, songwriter, record producer, and fashion designer.
Born in Atlanta and raised in Chicago, West gained recognition as a producer for Roc-A-Fella Records in the ea ...
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". Rappers
Nicki Minaj,
Big Sean
Sean Michael Leonard Anderson (born March 25, 1988), known professionally as Big Sean, is an American rapper. Anderson began his music career in 2007 and gained popularity in 2010 with his third mixtape '' Finally Famous Vol. 3: Big''. He then s ...
,
Drake, and
Lil Wayne are credited with the popularization of hashtag rap, while the style has been criticized by
Ludacris,
The Lonely Island
The Lonely Island is an American comedy trio, formed by Akiva Schaffer, Andy Samberg, and Jorma Taccone in Berkeley, California, in 2001. They have written for and starred in the American TV program ''Saturday Night Live'' (''SNL'').
The three ...
, and various music writers.
On September 13, 2013, a hashtag, #TwitterIPO, appeared in the headline of a ''
New York Times
''The New York Times'' (''the Times'', ''NYT'', or the Gray Lady) is a daily newspaper based in New York City with a worldwide readership reported in 2020 to comprise a declining 840,000 paid print subscribers, and a growing 6 million paid ...
'' front-page article regarding Twitter's
initial public offering
An initial public offering (IPO) or stock launch is a public offering in which shares of a company are sold to institutional investors and usually also to retail (individual) investors. An IPO is typically underwritten by one or more investme ...
.
[
]
In 2014
Bird's Eye foods released "Mashtags", a
mashed potato product with pieces shaped either like
or .
In 2019, the
British Ornithological Union
The British Ornithologists' Union (BOU) aims to encourage the study of birds ("ornithology") and around the world, in order to understand their biology and to aid their conservation. The BOU was founded in 1858 by Professor Alfred Newton, Henry ...
included as hash character in the design of its new Janet Kear Union Medal, to represent "science communication and social media".
[ ee attached image for explanation of the hash character/ref>
]
See also
* URI fragment
* Tagging
* Mentioning a user's profile by using @ tagging in blogging.
* Webring, an early-web decentralized mechanism to link websites with a common theme
* Folksonomy
* Social bookmarking
* Models of collaborative tagging
* Web 2.0
References
External links
* /tools.wmflabs.org/hashtags/search/artandfeminism Wikipedia internal hashtag search engine– for hashtags used in edit summaries
* Veszelszki, Ágnes 2016
#time, #truth, #tradition. An Image-text Relationship on Instagram: photo and hashtag
In: Benedek, András; Veszelszki, Ágnes (eds.): In the Beginning was the Image: The Omnipresence of Pictures: Time, Truth, Tradition. Frankfurt am Main: Peter Lang GmbH, Internationaler Verlag der Wissenschaften, pp. 139–150.
Infografika Hluboká Historie hashtagu
Infografika Historie hashtagu
Growing hashtags: Expanding outreach on Wikipedia
Wikimedia hashtag search
{{authority control
2010s slang
Collective intelligence
Computer jargon
Information retrieval techniques
Knowledge representation
Metadata
Reference
Social media
Web 2.0
Twitter