If there’s one factor that explains why people have an emotional bond with group-messaging phenom Slack that’s unusual for an enterprise tool, it’s the service’s polish and playful sensibility. Slack feels like a consumer app, not gray and emotionless business software. So it’s not the least bit surprising that Slack users have long clamored for something along the lines of Facebook’s Like button or Twitter’s Favorites: a way to instantly register approval for someone else’s post.
Now Slack is responding to those requests. But it’s doing so with a new feature that has the potential to do quite a bit more to change how people use Slack than a garden-variety Like button ever could. It’s called emoji reactions, and it lets you quickly respond to a post with a 
or a 
or a 
or any other emoji supported by Slack.
The service offers 722 emojis, so you can do a lot more than merely indicate that you enjoyed something. You could choose a frowny face registering several different degrees of disgust and/or alarm. Or a rocket or a panda or a burger or a baseball. Or, actually, anything–Slack allows you to upload your own custom emoji if the ones it provides are insufficient.
As with the Likes on a Facebook post, multiple reactions using the same emojis get aggregated, tallied, and appended to the bottom of the post. Which means that the result is quite different from Slack’s current emoji support, which treats even a solitary 
as a space-hogging new post unto itself, disconnected from whatever prompted it.
Emojis are normally associated with quirky self-expression, not mundane business communications. But Slack points out several ways they can let colleagues work together more efficiently–which is, after all, the whole idea behind the service. The tallying, for instance, allows them to be used for mini-polls in which people pick one of several emojis to register their vote. If someone asks you to perform a task, responding with a checkmark might be the swiftest way to indicate that you’ve taken action. And if enough coworkers use emoji reactions rather than text posts such as “Hi” or “Thanks,” it might clear out some of the clutter of a bustling Slack environment.
“It helps the more important messages stand out,” says Simon Vallee, a product manager at Slack. In the company’s own internal tests of the new feature–as you would assume, its employees live within Slack themselves–“we’ve found that it diminishes the amount of noise in a channel. It’s been a real boon.”
The new feature also includes a spruced-up version of Slack’s emoji picker, plus emoji reaction alerts in each user’s “Recent Mentions” notification center. It’s available immediately in the service’s browser-based desktop version. Users of the mobile apps will be able to add reactions to a post if someone else has already done so, but will need to wait for upcoming software updates to get full access.