Solitary confinement is a form of imprisonment in which an incarcerated person lives in a single cell with little or no contact with other people. It is a punitive tool used within the prison system to discipline or separate incarcerated individuals who are considered to be security risks to other incarcerated individuals or prison staff, as well as those who violate facility rules or are deemed disruptive. However, it can also be used as protective custody for incarcerated individuals whose safety is threatened by other prisoners. This is employed to separate them from the general prison population and prevent injury or death.

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.