“Whatever work you do, you can do it in Slack” is the first thing to greet you when you go to Slack’s website. It's a bold, exciting, intriguing, and perhaps ambiguous claim. According to its S-1 filing, the company is on a mission “to make people’s working lives simpler, more pleasant, and more productive.” Let’s discuss this without the distraction of financial numbers and operating metrics. So, what is Slack, and how is it disrupting the way people work?