Cleanliness is the absence of dirt, including dust, stains and a bad smell. In more recent times, since the germ theory of disease, it has also come to mean an absence of germs and other hazardous materials. It can apply to humans, animals, clothing, eating utensils, plates, pans, cups, etc., food, other movable objects, floors, windows, walls, toilets, etc.

Purposes of cleanliness are health, beauty, absence of bad smell, other comfort, avoidance of shame, and for avoiding spreading dirt and contaminants to oneself and other people, places or objects. In the case of windows the purpose is also transparency.

Washing is one way of cleaning, namely with water and often some kind of soap or detergent, often a different kind for different applications.

See also Broomstick, Brush, Hygiene, Remediation, Ritual purification, Vacuum cleaner.