Imprisonment is the restraint of a person's liberty, for any cause whatsoever, whether by authority of the government, or by a person acting without such authority. In the latter case it is "false imprisonment". Imprisonment does not necessarily imply a place of confinement, with bolts and bars, but may be exercised by any use or display of force (such as placing one in handcuffs), lawfully or unlawfully, wherever displayed, even in the open street. People become prisoners, wherever they may be, by the mere word or touch of a duly authorized officer directed to that end. Usually, however, imprisonment is understood to imply an actual confinement in a jail or prison employed for the purpose according to the provisions of the law.

Sometimes gender imbalances occur in imprisonment rates, with incarceration of males proportionately more likely than incarceration of females.