A prison, correctional facility, detention center[a] (US English), jail[b] (US and Australia), gaol (dated) (British English), penitentiary (sometime used in American English) or remand centre[c][d] is a facility in which inmates are forcibly confined and denied a variety of freedoms under the authority of the state. Prisons are most commonly used within a criminal justice system: people charged with crimes may be imprisoned until they are brought to trial; those pleading or being found guilty of crimes at trial may be sentenced to a specified period of imprisonment. Besides their use for punishing crimes, jails and prisons are frequently used by authoritarian regimes against perceived opponents.
The term prison or penitentiary is often used to describe institutions that incarcerate people for longer periods of time, such as many years, while jail is often used to describe institutions focused on confining people for shorter periods of time (e.g. for shorter sentences or while waiting for trial / sentencing). Prisons often have facilities that are more designed with long term confinement in mind in comparison to jails.
Prisons can be used as a tool of political repression to punish what are deemed political crimes, often without trial or other legal due process; this use is illegal under most forms of international law governing fair administration of justice. In times of war, prisoners of war or detainees may be detained in military prisons or prisoner of war camps, and large groups of civilians might be imprisoned in internment camps.