A SNAP file is a compressed software package created by Snapcraft, which is an app store used by developers to package and distribute apps for Linux. It contains an entire filesystem that is mounted by the snapd tool to run an application in Linux without being developed for Linux.

You will most likely only encounter SNAP files if you are a developer who packaged an app with Snapcraft or received a SNAP file to run an app in Linux. The SNAP file makes it easier for a user to run an app since it does not require installation and is not dependent on external resources to run. The snapd tool is a background service used to maintain and manage SNAP packages. You can install a SNAP package with the $ snap install command and delete a SNAP package with the $ snap remove command.