December 10, 2015 7:07 AM EST

#AskHerMore

JANUARY

Popularized by celebs such as Reese Witherspoon, Shonda Rhimes and Amy Poehler to demand that people stop focusing so much on women’s appearance

#JeSuisCharlie

JANUARY

Started to voice support for the victims of the Charlie Hebdo shooting (alongside #JeSuisAhmed)

#LoveWins

JUNE

Shared by millions after the U.S. Supreme Court ruling that legalized same-sex marriage

#YouStink

AUGUST

Inspired violent protests after residents of Beirut used it to blast the government for failing to collect trash efficiently

#StandWithPP

AUGUST

Took off amid efforts to defund Planned Parenthood, thanks in part to support from Kerry Washington, Lena Dunham and Elizabeth Banks

#RefugeesWelcome

SEPTEMBER

Spread by activists petitioning David Cameron to let more refugees into Britain, and supported by President Obama, Madeleine Albright and others

#IAmAChristian

OCTOBER

Tweeted by Ben Carson to unite the conservative base following reports that the Oregon college shooter was targeting Christians

#ConcernedStudent1950

NOVEMBER

Started by students at the University of Missouri to protest what they say is growing racism on U.S. campuses

#ItsJustACup

NOVEMBER

Mocked social-media users who were upset that Starbucks’ red holiday cups did not have Christmas imagery

#PorteOuverte

NOVEMBER

Used by Parisians to find and offer housing for people who needed shelter after the ISIS attacks

This appears in the December 21, 2015 issue of TIME.

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Write to Olivia B. Waxman at olivia.waxman@time.com.

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