Shut Down Your Office. You Now Work in Slack.

The messaging service first took over the digital work world. Now it’s everywhere.

Tracey Taylor, the managing editor of my hometown local news site Berkeleyside, is a reasonably hard-nosed veteran journalist, but she sounds a little wobbly at the knees as she tells me about her recent infatuation. She’s fallen hard — for an enterprise software service.

“I was away on a trip when we started using it,” she says. “Everyone was talking about how great it was, and at first I was annoyed. It took me about two days to see the value. Now, when someone on the team tries to contact me in any other way, I get annoyed with them — I just say, put it in Slack.”

Slack, a messaging tool designed for team collaboration, is the working digital world’s latest paramour. Slack is explicitly designed for the office, yet it feels like a friend. It’s business software that you don’t want to quit at the end of the day.

When we fall in love with a piece of software, we want to move in with it, and droves of infatuated users have shacked up with Slack. Now they’re importing more and more of their lives into it. Why switch to a different app to set a reminder, track your hours, keep up with Twitter, or tally a to-do list? Slack is what you already have open, all the time. Sure, the wreckage of past affairs (email, Microsoft Office, the desktop itself) litters our screens. But maybe this time will be different.

If you haven’t yet used Slack, it will not seem all that revolutionary; to the uninitiated, it still evokes “What’s the big deal?” responses. (Former Valleywag editor Sam Biddle, on Twitter: “No more interesting than our desk chairs.”) Slack does not come on like a heavy-duty digital disruptor. Above all, it’s a considerate program: It does things the way you’d want it to, often without your having to tell it — and if you want it to do something differently, it almost always lets you.

What a great partner! But it’s got some ideas of its own, too. It wants to limit the place of those old flames in your new life. It wants you to answer when it calls. It wants to get everything in the open — but, please, type it out. Also: It’s persuasive.

The prodigal child of IRC and Gmail, Slack is, primarily, a group-messaging tool with a memory. Its aubergine-and-teal screen simply and sensibly organizes teams of co-workers into public (within-the-company) channels and private discussions.

Everything public is searchable — so, “just through the regular process of communication,” as Slack founder Stewart Butterfield puts it, “the team builds an archive that’s incredibly valuable.”

Slack moves effortlessly across devices, keeping tabs on your “read”s and “unread”s without breaking a sweat. (Sounds simple, but it’s something competitors like Skype have had a hard time accomplishing.)When you drop a shared link into a message, Slack pulls in summaries, images and videos, a la Facebook. You can store files in it and find them easily (unlike your email attachments).

Off the shelf, you get integrations with dozens of other services — so that, say, piping in every bug report or help request or Twitter mention of your company’s name is a cinch. Developers can easily plug their favorite version-control and project-planning tools directly into the Slack brainstem. “Slash commands” — an update on old IRC practice — let you use Slack like a command line interface. This means that some workers can trade in their cumbersome time-tracking software for a simple “/done” in Slack, and others can use the venerable “/me” syntax to add stage directions to their messages. So if you type this:

Your coworkers see this:

Slack skipped right past the shallow end of the hockey-stick growth curve through a combination of whipsmart design, remarkable flexibility, and dashes of whimsy. (Slackbot, the app’s resident automaton, introduces itself by declaring that it is “pretty dumb, but tries to be helpful.”) Programming outfits, media organizations, and marketing teams quickly embraced Slack even before it was widely available. Invites were hot and hard to come by during a six-month beta that preceded the official launch in Feb. 2014.

A year later, Slack declared that, with half a million “daily active users,” it was the “fastest growing business app ever.” By mid-April, just two months later, the user number was clocking in at 750,000. Growth like that brought quick cash in the door: The company has raised more than $300 million in three rounds since the launch — the most recent at a valuation of nearly $3 billion. But Slack isn’t a revenueless dot-com bubble baby burning through investor dollars; the pricing model is “freemium,” and more than a quarter of its users are paid. (That looks like about $16 million in revenue at Slack’s basic rates — probably more, depending on how many pick higher-cost plans.)

Slack’s business story is impressive but, in this era of unicorn-herding, familiar. At this point, there’s little question that — barring global financial catastrophe or apocalypse — it will make its creators rich. The more interesting question is whether it can really, as it promises, make its users “less busy.”

Slack isn’t just infiltrating the office, or “gamifying” the office; it’s becoming the office. And its overnight success gives us a peek around the corner into the future of both work and online behavior. If there’s a way to move beyond notification overload and “context collapse” and many of the other ills that afflict our digital working lives circa 2015, Slack just might find it.

For a generation, most office work has happened in two venues: meetings and email. Slack maps a route around both of these time-sucking maelstroms.

Email is the easier target. Nobody loves email anymore, though everyone still uses it. But there is nothing inevitable about its place in the office. Think back to its arrival there two decades ago, if you’re old enough (I am). At first, it made no sense! If you thought of email as the digital equivalent of post-office mail, why on earth would you send it to the person sitting across from you? Why would you send a message all the way up to the server and back just to get it to the inbox of someone sitting 20 feet away from you?

That incredulity lasted about a day. Email worked, before long everyone had it, and it became the least-common-denominator of digital communications. You could get a lot done with it, too — before spam and email marketing and email notifications all went bananas. Email’s biggest drawbacks were that it was confusing (as legions of embarrassingly misdirected replies and forwards attest), and it piled up in guilt-inducing, neglected snowdrifts.