A military prison is a prison operated by a military. Military prisons are used variously to house prisoners of war, unlawful combatants, those whose freedom is deemed a national security risk by the military or national authorities, and members of the military found guilty of a serious crime. There are two types: penal and confinement-oriented, where captured enemy combatants are confined for military reasons until hostilities cease. Most militaries have some sort of military police unit operating at the divisional level or below to perform many of the same functions as civilian police, from traffic-control to the arrest of violent offenders and the supervision of detainees and prisoners of war.

A prison, also known as a jail, gaol, penitentiary, detention center, correction center, correctional facility, or remand center, is a facility where people are confined against their will and denied a variety of freedoms under the authority of the state, generally as punishment for various crimes. Authorities most commonly use prisons within a criminal-justice system: people charged with crimes may be imprisoned until their trial; those who have pled or been found guilty of crimes at trial may be sentenced to a specified period of imprisonment.