HygieneHygiene is the maintenance of healthful practices. In modern terminology, this is usually regarded as a particular reference to cleanliness.
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. 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 germs to oneself and other people, places or objects. In the case of windows the purpose is also transparency.
People usually wash themselves. Little children and sick and disabled people may be washed by someone else. For fun lovers etc. may wash each other. Often a shower is used, and/or a bathtub. More frequent is washing of just the hands, e.g. before and after preparing food and eating, after using the toilet, after handling something dirty, etc.
Hygiene has also commercial and cultural aspects. TV advertising has been launching campaigns in many countries trying to imprint in public opinion minds that only clean and sterile is healthy and safe.
Hygienic practices -- such as hand washing, and the use of boiled (and thus sterilized) water in medical operations -- have a profound impact on reducing the spread of disease. This is because they kill disease-causing microbes (germs), or remove them from the immediate surroundings. For instance, washing one's hands after using the toilet and before handling food reduces the chance of spreading E. coli bacteria and hepatitis A, both of which are spread from fecal contamination of food.
The use of antibacterial soap in the home is of doubtful benefit and may be harmful. Antibacterial soaps contain a low concentration of a chemical which purportedly kills bacteria. These chemicals may be similar to ones we want to use in fighting infection and their use in everyday cleansers may lead common bacteria to evolve resistance to these chemicals. Similar to antibiotic resistance, this would make antibiotics far less useful in combating infections.