A prison (from Old French prisoun) is a place in which people are physically confined and, usually, deprived of a range of personal freedoms. Imprisonment or incarceration is a legal penalty that may be imposed by the state for the commission of a crime. Other terms used are penitentiary, penalty school, correctional facility, remand centre, detention centre, and jail or gaol. In some legal systems some of these terms have distinct meanings. In the United States the difference between jails or detention facilities and prisons is primarily short-term and long term. Jails and detention facilities, under city or county jurisdiction, typically hold offenders awaiting trial or are serving short sentences. Correctional facilities and prisons are more often run by the state or federal governments and house offenders serving long-term sentences. Similarly Ontario, Canada, jails and detention centres are used to hold remanded prisoners awaiting trial, sentencing or other court proceedings. Jails are typically small facilities originally designed to serve the local community and have been gradually replaced with large regional detention centres. Jails and detention centres are run by the provincial government. Once an offender is sentenced, he or she would be transferred to either a provincial correctional centre (if the sentence is less than two years less a day) or a federal penitentiary (if the sentence is two years or more).

A criminal suspect who has been charged with or is likely to be charged with criminal offense may be held on remand in prison if he is denied or unable to meet conditions of bail, or is unable or unwilling to post bail. A criminal defendant may also be held in prison while awaiting trial or a trial verdict. If found guilty, a defendant will be convicted and may receive a custodial sentence requiring imprisonment.