Immutable means it does not change.

Presumably this means that the operating system is effectively read only.

This is good for applications where you want things to be very stable.

Say we find a bug in the operating system. What is the procedure for fixing the bug?

Deploy an updated, but immutable image.

Like, Partition1 has v1 and you boot, read only. Then the upgrade image goes in Partition2 and boots readonly.

You can still upgrade but every boot of the image is from the same fixed state. And you don't upgrade in-place.

They do "atomic" updates for immutable distributions, effectively treating an "apt update" always as an update for all components. There's some systems for this that usually require a reboot afterward to load the new system version.

Is this like a Live CD?