I can’t seem to wrap my head around (Docker) containers and especially their maintenance.
As I understand it, containers contain a stripped-down OS that shares some resources with the host?
Or is it more like a closed-off part of the file system?

Anyway, when I have several containers running on a host system,
Do I need to keep them all updated separately? If so, how?
Or is it enough to update the host system, and not worry about the containers?