Brig

The brig aboard a Galaxy-class.

A brig or holding cell is a type of prison on board a starship, space station or planetary facility. These are heavily-guarded rooms that employ either gates or force fields to keep those incarcerated segregated from the general population of the vessel. These areas are used to contain criminals, fugitives, and others who pose a security risk and must be detained. They are also used as a means of punishment within the Star Fleet ranks.