Solitary confinement is a practice where an individual prisoner is isolated in a cell by themselves.
It's a highly controversial practice that has been attacked by prisoner rights advocates as cruel and unusual punishment. Prisons defend the practice as a thoroughly effective means of controlling prisoners and ensuring prisoner compliance.
Solitary confinement can be part of an initial sentence for a serious crime. More often, however, solitary confinement is reserved as a punishment for poor behavior within prison.
A growing body of research surrounding the practice demonstrates the psychological harm caused to inmates held in solitary confinement. The practice is often used on political prisoners as a means of torture, or to force a prisoner into compliance. Despite the harms and recognition of the cruelty of the practice, solitary confinement persists as a commonly accepted tactic.