Canonical has released Slack as a Snap, which allows Slack to be installed and used on a greater variety of Linux distributions. Snapcraft is a command line tool that allows you to install containerised applications called Snaps on many different Linux distribution. Snap containers contain all the required dependencies that a program needs to run, it makes it very easy to create and distribute a single container that works on a variety Linux versions. For Canonical, it provides a greater user base for their Snapcraft service and for Slack, it allows a larger audience to use their service.
Source: https://www.bleepingcomputer.com/news/security/in-a-snap-slack-comes-to-linux-heres-how-to-install-it/