Following the terrorist attack on the Charlie Hebdo office in Paris, millions tweeted using the hashtag #JeSuisCharlie to honor the 12 victims and support their commitment to free speech and expression.

Watch use of the hashtag spread throughout France and the rest of Europe, then to the US, and finally to all corners of the globe, including the Middle East.

Twitter released this cool visualization, showing that the hashtag has been used about five million times. Despite some reports, however, #JeSuisCharlie is not the most used hashtag ever. Not even close. Over 32 million people used #WorldCupFinal as Germany beat Argentina and over 78 million people used #vote5sos to vote for teen rock band 5 Seconds of Summer at last year’s MTV Video Music Awards.

Of course, those are different kinds of events. #JeSuisCharlie ranks high when compared with other news events. During the peak of the Ice Bucket Challenge phenomenon last summer, #IceBucketChallenge was used just over 2 million times. #Ebola was used just under 2 million times on October 23rd and 24th, right after Craig Spencer was rushed to Bellevue Hospital in New York City and diagnosed with the disease. #Ferguson was used 3.5 million times in just a few hours following the grand jury decision not to indict officer Darren Wilson.

Hashtags are becoming a tool for spreading compassion globally. Following the hostage situation in Sydney last month, thousands tweeted the hashtag #illridewithyou as a gesture of solidarity with Muslims everywhere. After terrorists murdered 132 children at a school in Peshawar, Pakistan (the day after the Sydney crisis, as it turned out), the hashtag #IndiaWithPakistan spread on social media to signify that Indians stood by their neighbors, despite otherwise bitter relations between the two countries.

In the days after the Paris attacks, #JeSuisCharlie inspired the creation of #JeSuisAhmed to honor the Muslim police officer killed outside the Charlie Hebdo office. #JeSuisJuif followed to show solidarity with French Jews after the hostage crisis and subsequent killings at a Kosher supermarket, which highlighted the exodus of Jews from France due to perceived anti-Semitism.

Other hashtags have united people around different, far less constructive messages.