If you want to gauge the zeitgeist in 140 characters or less, check Twitter. The site, which counts about 320 million monthly active users, says that 79 percent of its accounts hail from outside of the U.S., the New York Times reported. Still, issues most pertinent to U.S. news, particularly social equality, topped the list of its most popular trends in 2015.

Here are some of the most popular topics, users and hashtags that defined this year's social consciousness:

1. #LoveWins

The U.S. Supreme Court's decision to give same-sex couples the right to marry prompted widespread celebration on social media, heralded by the hashtag #LoveWins.

2. #IStandWithAhmed

After 14-year-old Ahmed Mohamed was detained by police for bringing a homemade alarm clock to his school in Irving, Tex., the high school student received an outpouring of support on social media, with the creation of the #IStandWithAhmed hashtag.

3. #BlackLivesMatter

This hashtag allowed civil rights protestors to band together in outrage over the deaths of black men by police offers. Protests over racial violence in Ferguson, Mo. also were a popular topic on Twitter in 2014.

4. Caitlyn Jenner

After her Vanity Fair cover, Caitlyn Jenner's new Twitter account grew to more than 1 million followers more quickly than others. Now the former Olympian uses the account as a platform to speak about transgender issues.

5. Paris terror attacks

Tweets that sympathized with the year's two major terror attacks in Paris, using hashtags such as #PrayforParis and #JeSuisCharlie, allowed people to collectively grieve with the city of lights.

6. Harry Styles

The member of British boy band One Direction gained the year's most retweets when his bandmate, Zayn Malik, left the band in March. His message of "All the love as always" garnered more than 700,000 retweets. Malik's Tweet announcing his decision took second place.