Slack today is rolling out message threads inside its familiar chat window, allowing teams to have more focused conversations inside a new "flex pane" that appears next to the main chat. The feature, which has been a top request of Slack users, reflects the company's evolution from a simple communication tool to a place where an increasing amount of work gets done.

Threads are rolling out today across Slack's web, desktop, and mobile apps. The idea of message threading is not an original one — it is used by some of Slack’s rivals, such as Convo, and is a foundational principle of email, which Slack has noisily promised to kill. But Slack’s implementation of threads is novel, and arguably more useful, than most of its peers — even if it comes at the cost of having to pay more attention to Slack than before.

Every thread must be attached to a Slack message, and each message only supports one thread. To start one, hover over a Slack message until the context menu appears. (It's the same menu that you use to add reaction emoji or share a message.) Tap the new chat bubble and a thread will appear in a new pane to the right of the main chat.

By default, the person you're responding to is added to the thread. You can add others by mentioning their usernames, and follow threads you're interested in manually in the thread's ellipses menu (...). The thread resembles a public version of group direct messages — but unlike direct messages, threads can be searched.

Slack says threads help make public channels more readable by moving discussions about discrete topics into their own workspace. "It’s just really hard to read a channel where four conversations are happening at once," says Paul Rosania, the product lead for threads.

Perhaps the cleverest thing about Slack's version of threads is the way they can move back into public view. Any message inside a thread can be "sent back" to the public channel at the press of a button. A thread where employees were making a decision about where to have lunch, for example, might culminate with someone sending the group's pick back to the main channel so everyone else can see.

How much you use threads will depend on your company and your job. But employees at Slack, who have been testing threads for months, say they are meant to complement public channels — not replace them. Joshua Goldenberg, the company's head of design, told me that only 7 or 8 percent of his time in Slack has moved to threads.

Still, like many changes to Slack, threads will likely mean you spend more time using Slack. Threads come with their own unified inbox, located underneath "all unreads" on the left-hand pane, and notifications when you are added to a thread or there is activity in one that you follow. There is also the risk that threads will become very popular at your company, and you will be asked to weigh in on many things, instead of simply letting most discussions roll off your back the way you did in the channel-only days.

All of this is by design. Slack might have begun life as a glorified IRC channel, but it aspires to be the place where you do much of your work. For some people, says April Underwood, the company's head of product, "they're getting all their work done in Slack. They’re talking to each other, they’re taking advantage of notifications from dozens of applications that they rely on to get their work done, [and] they’re taking action on those notifications with message buttons. Slack is not a chat tool ... it's a place where people are producing work product, they’re collaborating around it, [and] they’re creating an archive that serves as a kind of brain for a company."

“Slack is not a chat tool. It’s a place where people are producing work.”

Here at The Verge, Slack mostly is a chat tool, and for me that's part of its charm. The nice thing about chat is that it usually only matters in the moment. One reason Slack could credibly claim to reduce email inside companies is that it encouraged people to drop their more ephemeral messages into chat, rather than email the entire staff. "I'm working from home" and "we're gathering in the break room for birthday cake" migrated into dedicated office ephemera channels, where they could be ignored, and the load on our inboxes lightened measurably.

Threads are for work that can't be ignored, and they are likely to demand your attention. The more they do, the less it will matter whether Slack killed email or not, because any time you saved in your inbox will now be spent doing work in Slack. From Slack's perspective, this is great news — when you're the place where all work gets done, customers will have a lot harder time canceling their subscriptions. And perhaps the chat-and-threads model will be faster and more efficient than your old system. But anytime I see a new inbox created in my life, I worry.

It's hard to imagine a more elegant implementation of threads than the one Slack designed. There's an undeniable need for a place within the app to have more focused discussions, particularly in the larger (and therefore noisier) companies that Slack is now courting. And Slack has been clear about its intentions to build an all-encompassing command console for the workplace from the start. I only wonder if one day we'll miss the days when Slack was something you could sometimes ignore.