Cleanliness is both the abstract

Abstraction

Abstraction is a process by which higher concepts are derived from the usage and classification of literal concepts, first principles, or other methods....

 state of being clean and free from dirt, and the process of achieving and maintaining that state.
Cleanliness may be endowed with a moral quality, as indicated by the aphorism

Aphorism

An aphorism is an original thought, spoken or written in a laconic and memorable form.The term was first used in the Aphorisms of Hippocrates...

 "cleanliness is next to godliness," and may be regarded as contributing to other ideals such as health

Health

Health is the level of functional or metabolic efficiency of a living being. In humans, it is the general condition of a person's mind, body and spirit, usually meaning to be free from illness, injury or pain...

 and beauty

Beauty

Beauty is a characteristic of a person, animal, place, object, or idea that provides a perceptual experience of pleasure, meaning, or satisfaction. Beauty is studied as part of aesthetics, sociology, social psychology, and culture...

. In emphasizing an ongoing procedure or set of habits for the purpose of maintenance and prevention, the concept of cleanliness differs from purity

Purity

Purity is the absence of impurity or contaminants in a substance or abstinence from vices in human character.Purity may also refer to:*Purity , an indication of the amount of other gases in a particular gas...

, which is a physical, moral, or ritual state of freedom from pollutants. Whereas purity is usually a quality of an individual or substance, cleanliness has a social dimension, or implies a system of interactions. "Cleanliness," observed Jacob Burckhardt

Jacob Burckhardt

Carl Jacob Christoph Burckhardt was a historian of art and culture, and an influential figure in the historiography of each field. He is known as one of the major progenitors of cultural history, albeit in a form very different from how cultural history is conceived and studied in academia today...

, "is indispensable to our modern notion of social perfection." A household or workplace may be said to exhibit cleanliness, but not ordinarily purity; cleanliness also would be a characteristic of the people who maintain cleanness or prevent dirtying.

On a practical level, cleanliness is thus related to hygiene

Hygiene

Hygiene refers to the set of practices perceived by a community to be associated with the preservation of health and healthy living. While in modern medical sciences there is a set of standards of hygiene recommended for different situations, what is considered hygienic or not can vary between...

 and disease prevention. Washing

Washing

Washing is one way of cleaning, namely with water and often some kind of soap or detergent. Washing is an essential part of good hygiene and health....

 is one way of achieving physical cleanliness, usually with water

Water

Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

 and often some kind of soap

Soap

In chemistry, soap is a salt of a fatty acid.IUPAC. "" Compendium of Chemical Terminology, 2nd ed. . Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford . XML on-line corrected version: created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN...

 or detergent

Detergent

A detergent is a surfactant or a mixture of surfactants with "cleaning properties in dilute solutions." In common usage, "detergent" refers to alkylbenzenesulfonates, a family of compounds that are similar to soap but are less affected by hard water...

. Procedures of cleanliness are of utmost importance in many forms of manufacturing.

As an assertion of moral superiority or respectability, cleanliness has played a role in establishing cultural values in relation to social class

Social class

Social classes are economic or cultural arrangements of groups in society. Class is an essential object of analysis for sociologists, political scientists, economists, anthropologists and social historians. In the social sciences, social class is often discussed in terms of 'social stratification'...

, humanitarianism

Humanitarianism

In its most general form, humanitarianism is an ethic of kindness, benevolence and sympathy extended universally and impartially to all human beings. Humanitarianism has been an evolving concept historically but universality is a common element in its evolution...

, and cultural imperialism

Cultural imperialism

Cultural imperialism is the domination of one culture over another. Cultural imperialism can take the form of a general attitude or an active, formal and deliberate policy, including military action. Economic or technological factors may also play a role...

.

Hygiene

Since the germ theory of disease

Germ theory of disease

The germ theory of disease, also called the pathogenic theory of medicine, is a theory that proposes that microorganisms are the cause of many diseases...

, cleanliness has come to mean an effort to remove germs and other hazardous materials

Hazardous waste

A hazardous waste is waste that poses substantial or potential threats to public health or the environment. According to the U.S. environmental laws hazardous wastes fall into two major categories: characteristic wastes and listed wastes.Characteristic hazardous wastes are materials that are known...

. A reaction to an excessive desire for a germ-free environment began to occur around 1989, when David Strachan put forth the "hygiene hypothesis

Hygiene hypothesis

In medicine, the Hygiene Hypothesis states that a lack of early childhood exposure to infectious agents, symbiotic microorganisms , and parasites increases susceptibility to allergic diseases by suppressing natural development of the immune system...

" in the British Medical Journal

BMJ

BMJ is a partially open-access peer-reviewed medical journal. Originally called the British Medical Journal, the title was officially shortened to BMJ in 1988. The journal is published by the BMJ Group, a wholly owned subsidiary of the British Medical Association...

. In essence, this hypothesis holds that dirt plays a useful role in developing the immune system; the fewer germs people are exposed to in childhood, the more likely they are to get sick as adults. The valuation of cleanliness, therefore, has a social and cultural dimension beyond the requirements of hygiene for practical purposes.

Industry

In industry, certain processes such as those related to integrated circuit

Integrated circuit

An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...

 manufacturing, require conditions of exceptional cleanliness which are achieved by working in cleanroom

Cleanroom

A cleanroom is an environment, typically used in manufacturing or scientific research, that has a low level of environmental pollutants such as dust, airborne microbes, aerosol particles and chemical vapors. More accurately, a cleanroom has a controlled level of contamination that is specified by...

s. Cleanliness is essential to successful electroplating

Electroplating

Electroplating is a plating process in which metal ions in a solution are moved by an electric field to coat an electrode. The process uses electrical current to reduce cations of a desired material from a solution and coat a conductive object with a thin layer of the material, such as a metal...

, since molecular layers of oil can prevent adhesion of the coating. The industry has developed specialized techniques for parts cleaning

Parts cleaning

Parts cleaning is essential to many industrial processes, as a prelude to surface finishing or to protect sensitive components. Electroplating is particularly sensitive to part cleanliness, since molecular layers of oil can prevent adhesion of the coating. ASTM B322 is a standard guide for cleaning...

, as well as tests for cleanliness. The most commonly used tests rely on the wetting behaviour of a clean hydrophillic metal surface. Cleanliness is also important to vacuum

Vacuum

In everyday usage, vacuum is a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than atmospheric pressure. The word comes from the Latin term for "empty". A perfect vacuum would be one with no particles in it at all, which is impossible to achieve in...

 systems to reduce outgassing

Outgassing

Outgassing is the release of a gas that was dissolved, trapped, frozen or absorbed in some material. As an example, research has shown how the concentration of carbon dioxide in the Earth's atmosphere has sometimes been linked to ocean outgassing...

. Cleanliness is also crucial for semiconductor

Semiconductor

A semiconductor is a material with electrical conductivity due to electron flow intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 103 to 10−8 siemens per centimeter...

 manufacturing.

See also

• Antiseptic
  Antiseptic
  Antiseptics are antimicrobial substances that are applied to living tissue/skin to reduce the possibility of infection, sepsis, or putrefaction...
  
  
• Aseptic technique
  Aseptic technique
  Aseptic technique refers to a procedure that is performed under sterile conditions. This includes medical and laboratory techniques, such as with microbiological cultures. It includes techniques like flame sterilization...
  
  
• Cleaner
  Cleaner
  Cleaner is the name of a German project specializing in electronic music. Formerly known as Cleen, Myer released several albums on the American industrial music record label, Metropolis Records, as well as the labels Zoth Ommog and Accession Records....
  
  
• Clean room
• Contamination control
  Contamination control
  Contamination control is the generic term for all activities aiming to control the existence, growth and proliferation of contamination in certain areas...
  
  
• Green cleaning
  Green cleaning
  Green cleaning refers to using cleaning methods and products with environmentally-friendly ingredients to preserve human health and environmental quality...
  
  
• Hygiene
  Hygiene
  Hygiene refers to the set of practices perceived by a community to be associated with the preservation of health and healthy living. While in modern medical sciences there is a set of standards of hygiene recommended for different situations, what is considered hygienic or not can vary between...
  
  
• Pollution
  Pollution
  Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...
  
  
• Environmental remediation
• Ritual purification
  Ritual purification
  Ritual purification is a feature of many religions. The aim of these rituals is to remove specifically defined uncleanliness prior to a particular type of activity, and especially prior to the worship of a deity...
  
  
• Waste management
  Waste management
  Waste management is the collection, transport, processing or disposal,managing and monitoring of waste materials. The term usually relates to materials produced by human activity, and the process is generally undertaken to reduce their effect on health, the environment or aesthetics...