Hygiene is a set of practices performed to preserve health. According to the World Health Organization (WHO), "Hygiene refers to conditions and practices that help to maintain health and prevent the spread of diseases." Personal hygiene refers to maintaining the body's cleanliness. Hygiene activities can be grouped into the following: home and everyday hygiene, personal hygiene, medical hygiene, sleep hygiene, and food hygiene. Home and every day hygiene includes hand washing, respiratory hygiene, food hygiene at home, hygiene in the kitchen, hygiene in the bathroom, laundry hygiene, and medical hygiene at home.