Workplace groups offer real-time chat and posts with threaded comments.

That's why, perhaps, the rest of Workplace is largely unchanged. The site still has a newsfeed, for instance, steered by the Facebook algorithm. According to McGinn, it gives employees a bird's-eye view of their company and surfaces content they might not have found on their own. If your employer is changing its healthcare policy, for instance, it'll be posted in a group that you probably don't visit every day. The feed can also highlight parts of the company that you weren't aware of -- an after-hours soccer club, for instance, or first-aid class -- that you want to join.

"When I'm in what I call 'serendipity mode', I go to the feed," McGinn said. "Maybe I'm not in this notification mode, I'm in the mode of 'Okay, so what else is going on?' Every now and then, it surfaces something that there is no way I would have naturally navigated to, through notifications or browsing my groups, or anything."

Workplace has groups, too, which are the Facebook equivalent of Slack channels. Every group has a real-time chat room and, crucially, a space or 'wall' for posts that can blossom into multi-media threads. A single post can house 50 different content types -- a staggering number, but one that pales in comparison to regular Facebook. Still, the composer allows enterprise users to post text, photos, documents and PDF files (which convert into swipe-able images.) Workplace has some unique features too, such as automatic file scanning for viruses and malware.

"When I'm in what I call 'serendipity mode', I go to the feed."

Employees can, of course, leave a 'like' or emoji-inspired reaction on these posts. According to McGinn, most Workplace customers use these tools to quickly convey feedback such as "I approve" or "yep, I've seen this." Some companies have built inventive workflows around them. One employer, for instance, has a group set up purely for travel approvals. Staff post their desired flights and wait for a manager to 'like' them, which tells the group admins to book the ticket and send over the confirmation details.

"And of course, all of this can happen asynchronously," McGinn explained. "You don't need to be in the same office; you can be in different time zones, and you don't expect everyone to pile in [and post] immediately."

Kyle McGinn, director of product for Workplace.

Facebook's advantages go further. Workplace has built-in live-streaming that allows CEOs to deliver big, company-wide announcements and, crucially, take employee-submitted questions in real-time. A small surf shop, McGinn said, once streamed a distributor meeting to show what stock they were ordering for next year. "The team felt like they were kind of there with him, and they felt fully informed," McGinn said. "Whereas what would've happened previously is he would've gone to that dealer meeting, come back and said, "Oh yeah, it was fine.'"

Workplace has Facebook's Safety Check feature, too, so staff can quickly check that their colleagues are okay after natural disasters and dangerous incidents. These features are useful but unusual for an enterprise-focused application. Smaller companies would consider them too expensive or inessential to justify the necessary development time and resources. The Workplace team, however, has the luxury of picking up and tweaking features that the consumer version of Facebook already developed. "We can make a few alterations that are more relevant for the workplace, and then we can launch it ourselves," McGinn said. "And we launch that in weeks or months, versus months and years."

"It's the equivalent of moving the milk aisle or vegetable aisle in the supermarket."

Facebook has been privately testing its redesign with select Workplace customers. At first, the feedback was mixed. Some people didn't like the change because, well, it was change. "It's the equivalent of moving the milk aisle or vegetable aisle in the supermarket," McGinn said. "Your default learned behavior has to change. And for the first week or two, it's pretty disruptive if you're used to shopping in that same place." These reactions are commonplace in the technology industry. When a popular site or piece of software -- including Facebook, Twitter and YouTube -- changes, there's always some backlash from people who prefer, or think they prefer, the previous design.

The Workplace team had to hold its nerve and see if people were still vexed after two or three days. Usually, critical testers would change their opinion and admit the redesign was simpler, cleaner and faster to navigate.

A subset of users commented that the new version had a lot of white space, though. "We dug into it quite a lot," McGinn said, "to try and understand if it was a problem. Was it the way the feedback was framed?" For the Workplace team, it was a "heart in mouth moment," he said. But with time, the designers realized that it was yet another example of 'you've moved the milk.' Apprehensive testers slowly changed their tune and admitted it was easier to focus on the core content displayed at the center of the page.