Slack, the instant messaging application, is seemingly ubiquitous among software developers and teams of various sizes and make ups nowadays. In recent years, its use has spread like wildfire and if there’s still a team that’s not using it and hanging on to things like Google Hangouts or Skype for Business, sooner or later someone on the team will suggest trying out Slack and the rest will be history. The fact that Slack is easy and free to set up makes the barrier of entry low and once a team starts, there’s usually no looking back. I’ve seen Slack take very deep roots in a corporate environment where the company tried to insist on using the “corporate standard” application, but to no avail: the developers basically ignored all such requests and insisted on using Slack.

But this post is not about how great Slack is (although it is arguably pretty cool and a great example for habit-forming application). It is about something else: After using the application for a few months with a globally distributed team, I noticed how it created a new mode of communication. Let me explain: Methods of human communication live on a scale of immediacy. On the far ends of this spectrum are the instantaneous, real-time methods such as voice and video (zero delay) and the method with the longest delay known as postal mail with days to weeks of delay (nothing is really any slower, assuming messages in bottles are out of scope).

The methods in the middle are a little more recent and interesting: There we have instant messages, SMS, and similar methods. While not exactly immediate or real-time, the expectation is usually that responses are received within minutes or maybe an hour at the longest. What about email? In my experience senders usually expect to hear back anywhere within 2 hrs to 1 business day.

So where does Slack fit in? It’s basically an instant messaging application, right? On the surface, yes. That’s where it all starts and that is certainly Slack’s core. One thing that makes Slack really sticky is the fact that you can transition to a real-time method. Involved in an intense back and forth with a colleague and the topic of conversation gets too complex or typing is getting too tedious? Well, you can now transition into Slack voice calls, video, or screen sharing (assuming you’re using the paid version).

That was – for a few months – a somewhat predictable development and evolution of use. But it didn’t stop there. There were times when something didn’t seem in need of an instant response and a Slack message seemed too “urgent”. So naturally I would think about resorting to email. But on second thought, the matter was more urgent and in need of attention than an email message would receive. So instead of typing up an email, I found myself posting to a specific Slack “channel” or writing a direct message to larger audience (which would’ve otherwise been a longer list of to’s and cc’s in an email). This was new: Slack now starting occupying the sweet spot between instant messages and emails on the continuum of communication immediacy. At least in my experience, there hadn’t really been any tools able to fill that gap. It was a new “mode” of communication, a hybrid between IM and emails, not so much based on the technology used but on the immediacy of the communication.

Considering how viral Slack has gone in the development community, it will be interesting to see how its capabilities will continue to evolve over time and how it may be catalyst to new and different ways to communicate amongst members of a team. And maybe that’s exactly where Slack could even break the mold again, i.e. transcending beyond teams and providing new methods of communication for random individuals that aren’t on a team? What if I could send a Slack message to my credit card company or my former classmate who moved out of state? Time will tell. Either way, this application certainly illustrates that after million of years the evolution of human communication is not only still happening, but even – driven by technology – accelerating.