
A hashtag is a metadata tag that is prefaced by the hash symbol, #. Hashtags are used on microblogging and photo-sharing services such as Twitter, Instagram and WeChat as a form of user-generated tagging that enables cross-referencing of content; that is, sharing a topic or theme. 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.

#Aufschrei ("outcry") is a German hashtag which went viral on the social media platform Twitter in 2013 with the goal of raising awareness about experiences of sexism in Germany. The Tweets began to appear in response to the publication of an article in which journalist Laura Himmelreich describes an invasive encounter with politician Rainer Brüderle of Germany's Free Democratic Party (FDP); within the German public, these tweets triggered a national debate on sexism, particularly experiences of everyday sexism.
#1Lib1Ref is a Wikipedia campaign inviting every librarian on Earth to participate in the online encyclopedia project, specifically improving articles by adding citations.

#2019GantiPresiden was a Twitter hashtag and social media campaign in which Indonesian users share their disapproval towards the Joko Widodo presidency. The main purpose of this campaign was a constitutional effort to replace the current president in the 2019 general election. The hashtag went viral after it was used by Prosperous Justice Party (PKS) politician Mardani Ali Sera on Twitter. In English, the term "Ganti Presiden" literally translates to "Change the President."

All Lives Matter (#AllLivesMatter) is a slogan that is associated with criticism of the Black Lives Matter movement.

Be Like Mike is a television advertisement for Gatorade starring American professional basketball player Michael Jordan. Created by advertising agency Bayer Bess Vanderwarker, it featured various children and adults playing basketball with Jordan, set to a song with lyrics about wishing one could be like the basketball player.

"Believe women" is an American political slogan arising out of the #MeToo movement. It refers to the necessity of accepting women's allegations of sexual harassment or sexual assault at face value. Sady Doyle, writing for Elle, argues that the phrase means "don't assume women as a gender are especially deceptive or vindictive, and recognize that false allegations are less common than real ones."

Black Lives Matter (BLM) is a decentralized political and social movement protesting against incidents of police brutality and all racially motivated violence against black people. While there are specific organizations such as the Black Lives Matter Global Network that label themselves simply as "Black Lives Matter", the Black Lives Matter movement comprises a broad array of people and organizations. The slogan "Black Lives Matter" itself remains untrademarked by any group. The broader movement and its related organizations typically advocate against police violence toward black people as well as for various other policy changes considered to be related to black liberation.

Blue Lives Matter is a countermovement in the United States advocating that those who are prosecuted and convicted of killing law enforcement officers should be sentenced under hate crime statutes. It was started in response to Black Lives Matter after the homicides of NYPD officers Rafael Ramos and Wenjian Liu in Brooklyn, New York on December 20, 2014.

Mulan is a 2020 American fantasy action drama film produced by Walt Disney Pictures. Directed by Niki Caro from a screenplay by Rick Jaffa, Amanda Silver, Lauren Hynek, and Elizabeth Martin, it is a live-action adaptation of the 1998 Walt Disney Animation Studios film of the same name, itself based on the Chinese folklore story Ballad of Mulan. The film stars Yifei Liu in the title role, alongside Donnie Yen, Tzi Ma, Jason Scott Lee, Yoson An, Ron Yuan, Gong Li, and Jet Li in supporting roles. In the film, Hua Mulan, the eldest daughter of an honored warrior, masquerades as a man to take her ailing father's place during a general conscription to counter the Rouran army in Imperial China.

Judith B. Newman is an American journalist and author. She writes about entertainment, relationships, parenthood, business, beauty, books, science, and popular culture. Her work has run through more than fifty publications, including The New York Times, Vanity Fair, Harper's, The Wall Street Journal, Allure and Vogue. Newman's books include the memoirs You Make Me Feel Like an Unnatural Woman: The Diary of a New (Older) Mother and To Siri With Love.

Clinton Body Count is a conspiracy theory asserting that former U.S. President Bill Clinton and his wife Hillary Clinton have had Americans assassinated, totaling as many as fifty or more. Many parts of it have been advanced by Newsmax publisher Christopher Ruddy, Congresswoman Marjorie Taylor Greene, and others. Such accusations have been around at least since the 1990s, when a film called The Clinton Chronicles, produced by Larry Nichols and promoted by Rev. Jerry Falwell, accused Bill Clinton of multiple crimes including murder. This conspiracy theory has been debunked by the Lakeland Ledger, the Chicago Tribune, Snopes and others, who point to detailed death records, the unusually large circle of associates that a president is likely to have, and the fact that many of the people listed had been misidentified, or were still alive. Others had no known link to the Clintons.

#DignidadLiteraria is a Spanish-language hashtag, used chiefly on Twitter, and a grassroots campaign for greater Latino inclusion in the U.S. publishing industry.

Dogs at polling stations or #dogsatpollingstations is a popular hashtag and Internet meme on social media during an election in the UK and other countries such as Australia. Typically, the dogs are photographed waiting for their owners outside the polling station and the pictures then posted on services such as Instagram or Twitter.

The #EleNão movement, also known as the protests against Jair Bolsonaro, were demonstrations led by women which took place in several regions of Brazil and, with less intensity, in other countries. The main goal was to protest against Jair Bolsonaro and his presidential campaign. The protests, which occurred on September 29, 2018, were the most numerous protests by women in Brazil and the largest popular concentration during the 2018 Brazilian general election.

End SARS is a decentralised social movement, and series of mass protests against police brutality in Nigeria. The slogan calls for the disbanding of the Special Anti-Robbery Squad (SARS), a notorious unit of the Nigerian Police with a long record of abuses. The protests which takes its name from the slogan started in 2017 as a Twitter campaign using the hashtag #EndSARS to demand the disbanding of the unit by the Nigerian government. After experiencing a revitalisation in October 2020 following more revelations of the abuses of the unit, mass demonstrations occurred throughout the major cities of Nigeria, accompanied by vociferous outrage on social media platforms. About 28 million tweets bearing the hashtag have been accumulated on Twitter alone. Solidarity protests and demonstrations by Nigerians in diaspora and sympathizers occurred in many major cities of the world. The protests is notable for its patronage by a demographic that is made of entirely young Nigerians. The movement has since expanded to include demands for good and accountable governance.

"Epstein didn't kill himself" is a phrase that summarizes various conspiracy theories surrounding the death of Jeffrey Epstein that dispute the official ruling of suicide by hanging. Epstein was an American financier and convicted sex offender with connections to powerful and wealthy people, and his reported suicide led to numerous hypotheses about the nature and cause of his death. The phrase became an Internet meme, gaining traction in November 2019 as more of the circumstances around his death became public. The most common theory asserts that the true cause of his death was homicide via strangulation, arranged by one or more co-conspirators to silence him. As a result, some people have used the phrase "Epsteined" to refer to reported suicides that they believe were feigned.

Euromaidan was a wave of demonstrations and civil unrest in Ukraine, which began on the night of 21 November 2013 with public protests in Maidan Nezalezhnosti in Kyiv. The protests were sparked by the Ukrainian government's decision to suspend the signing of an association agreement with the European Union, instead choosing closer ties to Russia and the Eurasian Economic Union. The scope of the protests soon widened, with calls for the resignation of President Viktor Yanukovych and his government. The protests were fueled by the perception of "widespread government corruption", "abuse of power", and "violation of human rights in Ukraine". Transparency International named President Yanukovych as the top example of corruption in the world. The situation escalated after the violent dispersal of protesters on 30 November, leading to many more protesters joining. The protests led to the 2014 Ukrainian revolution.

The Free Britney movement is a social movement to grant American singer Britney Spears autonomy from her ongoing conservatorship, which began in 2008. The movement became popular in 2019, after the emergence of allegations involving Spears's time in a psychiatric facility early in the year.

#GrabYourWallet is an organization and social media campaign that is an umbrella term for economic boycotts against companies that have any connections to Donald Trump in response to the leak of a lewd conversation between Donald Trump and Billy Bush on the set of Access Hollywood where he said "grab them by the pussy". The movement has particularly targeted Uber and Trump's daughter Ivanka Trump's clothing and shoe line, which was carried by Nordstrom before being indefinitely discontinued due to poor sales as a result of the boycott.

Hijabophobia is a type of religious and cultural discrimination against Muslim women who wear the hijab. The discrimination has had manifestations in public, working and educational places.

"I can't breathe" is a slogan associated with the Black Lives Matter movement in the United States. The phrase originates from the last words of Eric Garner, an unarmed man who was killed in 2014 after being put in a chokehold by a New York City Police Officer. A number of other Black Americans, such as Javier Ambler, Manuel Ellis, Elijah McClain, and George Floyd, have said the same phrase prior to dying during similar law-enforcement encounters. According to a 2020 report by the New York Times, the phrase has been used by over 70 people who died in police custody.

"Je suis Charlie" is a slogan and logo created by French art director Joachim Roncin and adopted by supporters of freedom of speech and freedom of the press after the 7 January 2015 shooting in which twelve people were killed at the offices of the French satirical weekly newspaper Charlie Hebdo. It identifies a speaker or supporter with those who were killed at the Charlie Hebdo shooting, and by extension, a supporter of freedom of speech and resistance to armed threats. Some journalists embraced the expression as a rallying cry for the freedom of self-expression.

The COVID-19 pandemic, which was first reported in the city of Wuhan, Hubei, China, in December 2019, has led to an increase in acts and displays of Sinophobia, as well as prejudice, xenophobia, discrimination, violence, and racism against people of East Asian and Southeast Asian descent and appearance around the world. With the spread of the pandemic and formation of hotspots, such as those in Asia, Europe, and the Americas, discrimination against people from these hotspots has been reported.

The Me Too movement, with variations of related local or international names, is a social movement against sexual abuse and sexual harassment where people publicize allegations of sex crimes. The phrase "Me Too" was initially used in this context on social media in 2006, on Myspace, by sexual assault survivor and activist Tarana Burke. Harvard University published a case study on Burke, called "Leading with Empathy: Tarana Burke and the Making of the Me Too Movement".

#Milifandom was an online campaign celebrating Ed Miliband, then-Leader of the Labour Party in the UK. The campaign was thought to have been started on Twitter by a seventeen-year-old student, Abby Tomlinson, with the aim of creating an online fandom for the leader. Supporters then used the Milifandom hashtag to declare their admiration for Miliband. The campaign has been viewed as an example of youth engagement in politics, as well as a backlash against negative portrayals of Miliband in the media.

The Milk Tea Alliance is an online democratic solidarity movement mainly made up of netizens from Hong Kong, Taiwan, Thailand, and Myanmar (Burma). It originally started as an internet meme, created in response to the increased presence of Chinese nationalist commentators on social media and has evolved into a dynamic multinational protest movement against authoritarianism and advocating democracy. Aside from the four main countries mentioned, the movement has also established a significant presence in South Korea, the Philippines, India, Malaysia, Indonesia, Belarus and Iran.

"Nevertheless, she persisted" is an expression adopted by the feminist movement, especially in the United States. It became popular in 2017 after the United States Senate voted to require Senator Elizabeth Warren to stop speaking during the confirmation of Senator Jeff Sessions as U.S. Attorney General. Senate Majority Leader Mitch McConnell made this remark during his comments following the vote.

"Piggate" refers to an uncorroborated anecdote that during his university years former British Prime Minister David Cameron inserted his penis and/or testicles into a dead pig's mouth as part of an initiation ceremony for the Piers Gaveston Society at Oxford University. The anecdote was reported by Michael Ashcroft and Isabel Oakeshott in their unauthorised biography of Cameron, Call Me Dave, attributing the story to an anonymous Member of Parliament who was a "distinguished Oxford contemporary" of Cameron's. Extracts from the book were published in the Daily Mail on 20 September 2015, prior to its publication.

On the night of 13 November 2015, Paris suffered a series of terror attacks. In reaction to those events, many individuals, governments, and other organisations around the world expressed their solidarity with France and with the victims. Many world leaders issued statements, mostly strongly condemning the attacks and vowing to stand by and support France. Public vigils took place in many international cities, and a number of world landmarks were illuminated in the colours of the French flag. Members of the public expressed their solidarity through social media by sharing images, notably the "Peace for Paris" symbol, designed by the French graphic designer Jean Jullien, and through the slogans, "Pray for Paris" and "Je suis Paris".

#SayHerName is a social movement that seeks to raise awareness for black female victims of police brutality and anti-black violence in the United States. Black women are 17% more likely to be stopped by police and 1.5 times more likely to be killed than their white counterparts. #SayHerName aims to highlight the gender-specific ways in which black women are disproportionately affected by fatal acts of racial injustice. In an effort to create a large social media presence alongside existing racial justice campaigns, such as #BlackLivesMatter and #BlackGirlsMatter, the African American Policy Forum (AAPF) coined the hashtag #SayHerName in December 2014.

Team Seas, stylized as #TeamSeas, is an international collaborative fundraiser project run by YouTubers MrBeast and Mark Rober as a follow up to TeamTrees with the goal to remove 30,000,000 pounds (14,000,000 kg) of marine debris by the end of 2021. It is the largest creator-led fundraising project on the internet to date, with thousands of creators alerting their viewers about the project. Partnering with the charities Ocean Conservancy and The Ocean Cleanup, TeamSeas hopes to inspire young people to make a change to the earth and its oceans to keep it trash free for future generations.

Team Trees, stylized as #TEAMTREES, is a collaborative fundraiser that raised 20 million U.S. dollars before 2020 to plant 20 million trees. The initiative was started by American YouTubers MrBeast and Mark Rober, and was mostly supported by YouTubers. All donations go to the Arbor Day Foundation, a tree-planting organization that pledges to plant one tree for every U.S. dollar donated. The Arbor Day Foundation began planting in January 2020 and plans to end "no later than December 2022". It is estimated that 23 million trees would take up 210 km2 (81 sq mi) of land, absorb around 1.6 million tons of carbon and remove 116 thousand tons of chemical air pollution from the atmosphere.
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.

We Said Enough or WeSaidEnough is a nonprofit organization that was founded in 2017. It is dedicated to eliminating discrimination, sexual harassment and assault within employment and academic settings. We Said Enough is based in Sacramento, California.

#WeThe15 is a global human rights movement which aims to make persons with disabilities, who make up 15% of the world's population, visible. An initiative of the International Paralympic Committee and the International Disability Alliance, it is supported, by a number of organisations from the world of disability sports, disability rights, non-governmental and governmental organisations. It was launched as part of the 2020 Summer Paralympics in 2021. Landmarks across the world were lit up in purple to coincide with the opening ceremony. The movement was given particular focus during the closing ceremony.

#YesAllWomen is a Twitter hashtag and social media campaign in which users share examples or stories of misogyny and violence against women. First used in online conversations about misogyny following the 2014 Isla Vista killings, the hashtag was popular in May 2014, and was created partly in response to the Twitter hashtag #NotAllMen. #YesAllWomen reflected a grassroots campaign in which women shared their personal stories about harassment and discrimination. The campaign attempted to raise awareness of sexism that women experience, often from people they know.