A month after Mark Zuckerberg announced Facebook's plans to roll out some sort of "dislike" button, the company is now testing the feature with users in Ireland and Spain. Called "reactions," the feature introduces six cartoon emoji you can use in responding to friends' posts: love, haha, yay, wow, sad, and angry. To use the feature, you long-press the like button until the six reactions pop up, and you choose one from there. Posts now show reaction counts alongside the number of comments — 10 likes, four wows, two hahas, and so on.

Facebook planned to announce the news later today, but it leaked early, leaving me with a notebook full of reporting and not much to do with it — other than share it with you, cherished readers of The Verge dot com! So here are the most interesting things I learned about the it's-totally-not-a-dislike button, taken from my conversation with Adam Mosseri, who leads product development for the News Feed.

5. Facebook users requested reactions beyond the like by constantly filing bug reports. Usually when we hear about Facebook-related outrage, it's because of some new feature they hate. But Facebook users demand features, too, and over the years few have been requested more than an expanded range of reactions. A fair number of people saw the lack of a haha as an actual software bug, and they expressed this by regularly filing bug reports with the site.

People saw the lack of a haha as an actual software bug

4. Facebook decided on its initial set of reactions by scanning your one-word comments. How did Facebook decide on the initial set of reactions to test with people? It had a pair of interesting signals to analyze. The first was your one-word comments. Haha, yay, wow, sad — these popped up a lot, and gave Facebook a roadmap for deciding which emoji to include.

3. Facebook also tracked the emotional sentiments of the sticker comments you were leaving on your friends' posts. The addition of sticker comments last year gave Facebook another signal as it developed reactions. Stickers are all tagged with emotional sentiments — it's why Facebook's sticker search works so well — and so it was easy for the company to see which sentiments were most popular.

Ireland and Spain are relatively isolated

2. The feature is rolling out to Spaniards and the Irish because they have no friends in other countries. For a company of Facebook's size, testing a feature like reactions with small groups is tricky. If I can react to your post with a haha, but you can't see my haha because you're not in the test group, Facebook is effectively broken. That's why Facebook tests features in countries where most of its users don't have friends outside the country. Ireland and Spain are relatively isolated in this way, and that's why they're getting reactions first.

1. People didn't really want a dislike button. The most obvious reaction for Facebook to add would seem to be the like button's equal and opposite reaction — the dislike. But "dislike" turns out to be less useful than it first appears, because it's not specific enough. "If you see something sad you could dislike it," Mosseri says. "But we find in practice people would rather send sympathy." Likewise, if you dislike a post because it makes you angry, you'd probably rather sound off with the anger emoji.

A couple things that didn't come up in my interview, but are probably worth saying: Facebook's reactions borrow heavily from Path, which had a similar system from the beginning. And there's probably at least one unmentioned reason why there isn't a true "dislike" button — Facebook doesn't want to encourage you to troll your friends by giving them a thumbs-down every time they say something stupid on Facebook. Could lead to less Facebook usage! Wherever they came from, though, and whatever they look like, I expect people will embrace our brave new post-like world, assuming the Irish and Spanish don't ruin it for the rest of us.

Haha.