Solitary confinement, colloquially referre to in American English as "the hole" or "the pound" (or in British English "the block"), is a punishment or special form of imprisonment in which a prisoner is denied contact with any other persons, excluding members of prison staff. Usually cited as an additional measure of protection (of society) from the criminal, it has also been called a form of torture. In some cases it is also used to protect the prisoner from others.