A Bouffant Cap is traditionally used to protect a complicated hairstyle while sleeping or showering. It is also used by the medical profession and in food preparation, keeping stray hairs under the cap. It is a hat whose function is to keep stray hair in and water or other contaminants out. It resembles a bag with a gathered elastic opening that covers the hair and fits snugly around the hairline. Bouffant Cap is a loose cap, so called because of its puffy shape, typically secured around the head with elastic, and frequently used in clean rooms, food service, and other settings to contain loose hair.