Facebook is about to shake up one of its most iconic symbols: the “like” button.

After months of speculation—and even leaks of early tests—the social network is finally giving users more options for reacting to all the baby photos, exasperating news stories, and cute kitten videos posted on the service. Now, they will be able to select one of six icons to express how they feel.

Along with the famous light blue thumb, the icons now include a read heart (“love”), a laughing face (“haha”), a surprised face (“wow”), a tearing face (“sad”), and an angry face (“angry”). To select one, users hover above or tap the “like” button until a menu of options pop up.

Facebook Reactions on Mobile

Facebook chose the five newcomers after roughly a year of brainstorming, data crunching, and various tests, Facebook News Feed engineering director Tom Alison told Fortune in an interview. In particular, the team took a deep look at trends in user comments, especially short comments of one to three words, and the cartoon-like image some people use in place of comments that Facebook introduced in 2014.

“It became pretty clear that it wasn’t going to be about ‘like’ or ‘dislike,’ and it wasn’t going to be 100 reactions,” Alison said about his team’s decision. In the end, it was about keeping things simple, he added.

Facebook also wanted its new options to be universal. Today, the social network is available in almost all countries, and in more than 70 languages. As part of its research, Facebook ran tests in a handful of countries including Spain, Ireland, and the Philippines to see how the new icons translated across languages and cultures. Early tests with reactions “yay!” and “confused,” for example, didn’t fare well with all users, according to Alison, so they didn’t make the cut.

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Since Facebook first introduced the “like” button in early 2009, some users have clamored for a “dislike” button. However, Facebook CEO Mark Zuckerberg has dismissed the idea largely over concerns that it would make online bullying easier, something social media services already work hard to combat.

But according to former Facebook designer Soleio Cuervo, who is often credited for the original “like” button’s design, the delay in adding alternatives hasn’t been because of sheer stubbornness.

“It’s not like Facebook was religious about it being a single option,” he told Fortune in an interview. Although he’s yet to try the new options, he says they appear to be very much in the spirit of the original button. “I think it’s a terrific idea,” he added.

The shift to mobile devices is also critical to making the new buttons work. In 2009, smartphones had barely caught on, Facebook had no mobile strategy, and Cuervo’s team was thinking in terms of what worked best for desktop computers.

“The ‘like’ button was for a point-and-click environment,” he explained, while the new reactions seem to be designed for smartphone users.

Still, the new options are a big departure from Facebook’s lone “like” button, and are likely to anger some users. It’s also unclear how Facebook will use the reactions to tailor what users see in their personalized News Feeds. While “likes” have been interpreted as positive signals for Facebook’s algorithm, the new reactions could bring more nuance. For the time being, Facebook won’t distinguish between the different buttons, but down the line, they could be used to help avoid incidents like photos of dead family members appearing in a user’s year-end photo montage just because they received at lot of “likes” as a form of empathy.

But for now, Facebook is focused on rolling out the new reactions buttons globally over the next few days.

An earlier version of this article misquoted former Facebook designer Soleio Cuervo about Facebook’s philosophy on adding alternatives to its “like” button. He said the company was always open to other “options,” not “accents.” The article has been updated.