Isolation

From Prisonblock

Isolation is the jail within a jail. If you get caught doing a crime for instance, you will be thrown into isolation. You may also be placed into isolation by a member of the Staff for misbehaving. The length of your stay will depend on the severity of the infraction.

While you are in isolation your stats do not replenish every tick and you can't do anything other than browse the forums and your inventory.

Unless you are placed in isolation by a staff member, you can use favors bribe the Warden for an early release.