/dev is for device files, ie special files that let you communicate directly with a physical piece of hardware
/etc is for configuration files, ie the comments tell how to setup a device or application
/var is for variable files, ie files who’s content is regularly changing, the primary example is logs, but there are a lot of other files that land in /var (some are moving to /run, though)
What’s diff between device files vs config files vs variable files?
/dev is for device files, ie special files that let you communicate directly with a physical piece of hardware
/etc is for configuration files, ie the comments tell how to setup a device or application
/var is for variable files, ie files who’s content is regularly changing, the primary example is logs, but there are a lot of other files that land in /var (some are moving to /run, though)
Two important things under /var are /var/spool for printing and /var/mail