Twitter turns 10 Monday and what a decade it has been. The social media site that limits posts to 140 characters has changed the way people share breaking news, organize social movements and come together in times of tragedy.

Created in 2006 by Evan Williams, Noah Glass, Jack Dorsey and Biz Stone, the platform now has 320 million monthly active users.

One reason for its popularity is that “hashtags” allow people to track topics with just a click, and anyone can create one by hitting # on their keyboard.

Twitter creates year-in-review websites showcasing the most used hashtags each year. As it celebrates its birthday, here’s a look at the most popular hashtags and retweets since hashtags took off in 2009 and retweets in 2010.

2015

  • #PrayforParis and #PorteOuverte were used after the November terrorist attacks in Paris to show support for the city and offer people a place to stay if necessary.
  • #BlackLivesMatter helped to spread a major social movement after accusations of police brutality in the U.S.
  • #LoveWins followed the Supreme Court’s decision to legalize same-sex marriage in the U.S.
  • #IStandWithAhmed was used by everyone from Canadian Astronaut Chris Hadfield to U.S. President Barack Obama after a 14-year-old Texas boy was detained for bringing a homemade clock to school.
  • #BlueandBlack faced off against #WhiteandGold when a picture of a striped dress went viral and people saw it as different colours.

The top retweeted tweet ended up being one from One Direction’s Harry Styles after Zayn Malik announced he was leaving the group.

2014

  • #MH370 was a Malaysian Airlines flight that mysteriously disappeared.
  • Later that year #MH17, another Malaysian Airlines flight, was shot down over Ukraine.
  • People from all over the world used #Sochi2014 to discuss the 2014 Winter Olympic Games.
  • #BringBackOurGirls was used by celebrities like Amy Poehler and Ellen Degeneres to show support after more than 200 girls were kidnapped by Boko Haram in Nigeria.
  • #Ferguson brought powerful tweets and images from protests surrounding the death of Ferguson, Mo., teenager Michael Brown.

Ellen’s infamous Oscars tweet was the most retweeted and liked tweet of 2014 – and of all time – with a selfie including actors Bradley Cooper and Brad Pitt and actresses Jennifer Lawrence and Meryl Streep.

2013

  • #SFBatKid followed a five-year-old boy’s day saving San Francisco as “Bat Kid,” fulfilling his wish with the help of the Make A Wish Foundation
  • #RoyalBaby surged with tweets after the birth of Prince George.
  • Following the Boston Marathon bombings and subsequent manhunt, the hashtag #BostonStrong was used to signify the strength of Boston and the rest of the world uniting in support.
  • California voted no on #Prop8, making same-sex marriage legal in California.
  • #Sharknado was tweeted out during the premier of the surprisingly popular made-for-television movie.

News of The Fast and the Furious star Paul Walker’s death was the most retweeted tweet of 2013, linking to Walker’s Facebook page.

2012

  • #London2012 was used during the 2012 Summer Olympic Games as people watched their countries compete.
  • #Sandy became a popular hashtag when the superstorm swept through the eastern coasts of the United States and Canada.
  • The #Endeavour space shuttle hitched a ride on a 747 to Los Angeles and the hashtag was used by many people taking pictures of it as it flew over cities.
  • #KONY2012 made a massive impact with a strong social media campaign from Invisible Children to find and arrest Joseph Kony, the leader of the Ugandan Lord’s Resistance Army.

U.S. President Barack Obama celebrated his re-election with a the most popular retweet of 2013 featuring a picture of him and the First Lady with three simple words.

2011

  • #Jan25 symbolized the one-year anniversary of the demonstrations in Egypt protesting then-President Hosni Mubarak.
  • Later that year, #Egypt was used during the election which voted in Muslim Brotherhood’s Mohammed Morsi.
  • #tigerblood and #winning were popular after the viral tweets and interviews from then newly-fired Charlie Sheen from his sitcom Two and a Half Men.”
  • The hashtag #Japan followed along with magnitude 9.0 earthquake and tsunami that caused the Fukushima Daiichi nuclear disaster.
  • Although not following a specific hashtag, the death Osama Bin Laden garnered a lot of attention.

The most popular tweet was a promoted tweet from the fast-food chain Wendy’s, asking for RTs to support kids in foster care.

2010

  • The #HaitiEarthquake hashtag rose from the magnitude 7.0 earthquake that displaced millions of people.
  • After a mine collapsed in Chile the hashtag #ChileanMinersRescue followed the miners for 69 days until the 33 men were rescued.
  • #Vuvuzela became a huge trend during the FIFA World Cup 2010, where the sound of the plastic instruments caused a lot of discussion.
  • #GulfOilSpill began trending when an explosion occurred at a BP-operated oil rig.
  • Julian Assange created #Wikileaks by publishing leaked documents that alleged government misconduct.

In light of the #GulfOilSpill, comedian Stephen Colbert tweeted his thoughts on the Deepwater Horizon disaster.

2009

  • The viral breakout of the year ended up being the #SwineFlu or the H1N1 influenza virus.
  • #inaug09 followed the historic inauguration of U.S. President Barack Obama.
  • #E3 or the Electronic Entertainment Expo saw the release of Halo: Reach and Super Mario Galaxy: 2.
  • #IranElection became a massive hashtag as people shared information on upcoming protests in light of the election.

Bonus

A top retweeted tweet of 2010, now deleted, was a simple one from Kanye West, expressing his regret for storming the stage while Taylor Swift accepted the award for Best Female Video at the 2009 MTV Video Music Awards. He proceeded to let everyone know that Beyoncé had the best video. The tweet simply said, “I’m sorry Taylor.”