Hot racking (also known as hot bunking or hot bedding) is the sanctioned practice within military organizations of assigning more than one crew member to a bed or "rack" to reduce berthing (sleeping) space. The practice dates back at least to the sixteenth century, and today is particularly applied aboard submarines, where maximization of space is especially important. Generally, the lowest ranking members of the crew are required to hot rack. Hot racking is sometimes utilized in jails and prisons to deal with overcrowding.