Hand washing or hand hygiene is the act of cleaning one’s hands with or without the use of water or another liquid, or with the use of soap for the purpose of removing soil, dirt, and/or microorganisms. The spelling “handwashing” in one word is also common.

Medical hand hygiene pertains to the hygiene practices related to the administration of medicine and medical care that prevents or minimizes disease and the spreading of disease. The main medical purpose of washing hands is to cleanse the hands of pathogens (including bacteria or viruses) and chemicals which can cause personal harm or disease. This is especially important for people who handle food or work in the medical field, but it is also an important practice for the general public.

People can become infected with respiratory illnesses such as influenza or the common cold, for example, if they do not wash their hands before touching their eyes, nose, or mouth. Indeed, the Centers for Disease Control and Prevention (CDC) has stated: “It is well documented that one of the most important measures for preventing the spread of pathogens is effective hand washing.” As a general rule, hand washing protects people poorly or not at all from droplet- and airborne diseases, such as measles, chickenpox, influenza, and tuberculosis. It protects best against diseases transmitted through fecal-oral routes (such as many forms of gastroenteritis) and direct physical contact (such as impetigo).

Symbolic hand washing, using water only to wash hands, is a part of ritual hand washing featured in many religions, including Hinduism in Judaism.