Hygiene refers to the practice of hand washing with soap and water. Access to sufficient quantity and quality of water with which one can wash hands will reduce risks of contamination and will reduce the chances of diarrhoea and enteric illnesses. Washing of face with water is also essential for  controlling trachoma. In countries where infection of eyes with chlamydia trachomatis is common (C. trachomatis is the commonest cause of infectious blindness), washing of face with cold clean water is a preventive measure. Washing of hands with soap and water is also practiced before eating, cooking, and for surgical practices and essential for physicians and nurses while examination of patients. The act of washing one's hands with soap and water prevents bacteria and other organisms to contaminate food or wounds.