In human social behavior, discrimination is treatment or consideration of, or making a distinction towards, a person based on the group, class, or category to which the person is perceived to belong. These include age, caste, colour, criminal record, height, disability, ethnicity, family status, gender identity, generation, genetic characteristics, marital status, nationality, race, religion, sex, sexual orientation, and social class. Discrimination consists of treatment of an individual or group, based on their actual or perceived membership in a certain group or social category, "in a way that is worse than the way people are usually treated".^[1] It involves the group's initial reaction or interaction going on to influence the individual's actual behavior towards the group leader or the group, restricting members of one group from opportunities or privileges that are available to another group, leading to the exclusion of the individual or entities based on illogical or irrational decision making.^[2]

Discriminatory traditions, policies, ideas, practices and laws exist in many countries and institutions in every part of the world, including in territories where discrimination is generally looked down upon. In some places, controversial attempts such as quotas have been used to benefit those who are believed to be current or past victims of discrimination—but they have sometimes been called reverse discrimination.

The term discriminate appeared in the early 17th century in the English language. It is from the Latin discriminat- 'distinguished between', from the verb discriminare, from discrimen 'distinction', from the verb discernere.^[3] Since the American Civil War the term "discrimination" generally evolved in American English usage as an understanding of prejudicial treatment of an individual based solely on their race, later generalized as membership in a certain socially undesirable group or social category.^[4] The word "discrimination" derives from Latin, where the verb discrimire means "to separate, to distinguish, to make a distinction".

Moral philosophers have defined discrimination as disadvantageous treatment or consideration. This is a comparative definition. An individual need not be actually harmed in order to be discriminated against. They just need to be treated worse than others for some arbitrary reason. If someone decides to donate to help orphan children, but decides to donate less, say, to black children out of a racist attitude, then they would be acting in a discriminatory way despite the fact that the people they discriminate against actually benefit by receiving a donation.^[5][6] In addition to this discrimination develops into a source of oppression. It is similar to the action of recognizing someone as 'different' so much that they are treated inhumanly and degraded.^[7]

Based on realistic-conflict theory^[8] and social-identity theory,^[9] Rubin and Hewstone^[10] have highlighted a distinction among three types of discrimination:

The United Nations stance on discrimination includes the statement: "Discriminatory behaviors take many forms, but they all involve some form of exclusion or rejection."^[11] International bodies United Nations Human Rights Council work towards helping ending discrimination around the world.

Ageism or age discrimination is discrimination and stereotyping based on the grounds of someone's age.^[12] It is a set of beliefs, norms, and values which used to justify discrimination or subordination based on a person's age.^[13] Ageism is most often directed towards old people, or adolescents and children.^[14][15]

Age discrimination in hiring has been shown to exist in the United States. Joanna Lahey, professor at The Bush School of Government and Public Service at Texas A&M, found that firms are more than 40% more likely to interview a young adult job applicant than an older job applicant.^[16] In Europe, Stijn Baert, Jennifer Norga, Yannick Thuy and Marieke Van Hecke, researchers at Ghent University, measured comparable ratios in Belgium. They found that age discrimination is heterogeneous by the activity older candidates undertook during their additional post-educational years. In Belgium, they are only discriminated if they have more years of inactivity or irrelevant employment.^[17]

In a survey for the University of Kent, England, 29% of respondents stated that they had suffered from age discrimination. This is a higher proportion than for gender or racial discrimination. Dominic Abrams, social psychology professor at the university, concluded that ageism is the most pervasive form of prejudice experienced in the UK population.^[18]

According to UNICEF and Human Rights Watch, caste discrimination affects an estimated 250 million people worldwide.^[19][20][21] Discrimination based on caste, as perceived by UNICEF, is mainly prevalent in parts of Asia, (India, Sri Lanka, Bangladesh, China, Pakistan, Nepal, Japan), Africa and others.^[19] As of 2011, there were 200 million Dalits or Scheduled Castes (formerly known as "untouchables") in India.^[22]

Discrimination against people with disabilities in favor of people who are not is called ableism or disablism. Disability discrimination, which treats non-disabled individuals as the standard of 'normal living', results in public and private places and services, education, and social work that are built to serve 'standard' people, thereby excluding those with various disabilities. Studies have shown, employment is needed to not only provide a living but to sustain mental health and well-being. Work fulfils a number of basic needs for an individual such as collective purpose, social contact, status, and activity.^[23] A person with a disability is often found to be socially isolated and work is one way to reduce isolation.

In the United States, the Americans with Disabilities Act mandates the provision of equality of access to both buildings and services and is paralleled by similar acts in other countries, such as the Equality Act 2010 in the UK.

Diversity of language is protected and respected by most nations who value cultural diversity. However, people are sometimes subjected to different treatment because their preferred language is associated with a particular group, class or category. Notable examples are the Anti-French sentiment in the United States as well as the Anti-Quebec sentiment in Canada targeting people who speak the French language. Commonly, the preferred language is just another attribute of separate ethnic groups. Discrimination exists if there is prejudicial treatment against a person or a group of people who either do or do not speak a particular language or languages.

Another noteworthy example of linguistic discrimination is the backdrop to the Bengali Language Movement in erstwhile Pakistan, a political campaign that played a key role in the creation of Bangladesh. In 1948, Mohammad Ali Jinnah declared Urdu as the national language of Pakistan and branded those supporting the use of Bengali, the most widely spoken language in the state, as enemies of the state.^[24]

Language discrimination is suggested to be labeled linguicism or logocism. Anti-discriminatory and inclusive efforts to accommodate persons who speak different languages or cannot have fluency in the country's predominant or "official" language, is bilingualism such as official documents in two languages, and multiculturalism in more than two languages.

Discrimination based on a person's name may also occur, with researchers suggesting the presence of discrimination based on a name's meaning, its pronunciation, its uniqueness, its gender affiliation, and its racial affiliation.^{[25][26][27][28][29]} Research has further shown that real world recruiters spend an average of just six seconds reviewing each résumé before making their initial "fit/no fit" screen-out decision and that a person's name is one of the six things they focus on most.^[30] France has made it illegal to view a person's name on a résumé when screening for the initial list of most qualified candidates. Great Britain, Germany, Sweden, and the Netherlands have also experimented with name-blind résumé processes.^[31] Some apparent discrimination may be explained by other factors such as name frequency.^[32] The effects of name discrimination based on a name's fluency is subtle, small and subject to significantly changing norms.^[33]

Discrimination on the basis of nationality is usually included in employment laws^[34] (see above section for employment discrimination specifically). It is sometimes referred to as bound together with racial discrimination^[35] although it can be separate. It may vary from laws that stop refusals of hiring based on nationality, asking questions regarding origin, to prohibitions of firing, forced retirement, compensation and pay, etc., based on nationality.

Discrimination on the basis of nationality may show as a "level of acceptance" in a sport or work team regarding new team members and employees who differ from the nationality of the majority of team members.^[36]

In the GCC states, in the workplace, preferential treatment is given to full citizens, even though many of them lack experience or motivation to do the job. State benefits are also generally available for citizens only.^[37] Westerners might also get paid more than other expatriates.^[38]

Racial and ethnic discrimination differentiates individuals on the basis of real and perceived racial and ethnic differences and leads to various forms of the ethnic penalty.^[39][40] It has been official government policy in several countries, such as South Africa during the apartheid era. Discriminatory policies towards ethnic minorities include the race-based discrimination against ethnic Indians and Chinese in Malaysia^[41] After the Vietnam war, many Vietnamese refugees moved to the United States, where they face discrimination.^[42]

As of 2013, aboriginal people (First Nations, such as the Métis, and Inuit) comprise 4 percent of Canada's population, but they account for 23.2 percent of the country's total federal prison population.^[43] According to the Australian government's June 2006 publication of prison statistics, Aborigines account for 24% of the overall prison population in Australia.^[44]

In 2004, the Māori made up just 15% of the total population of New Zealand but they accounted for 49.5% of all prisoners in the country. Māori were entering prison at eight times the rate of non-Māori.^[45] A quarter of the people in England's prisons are members of ethnic minority groups. The Equality and Human Rights Commission found that in England and Wales as of 2010, a black person was five times more likely to be imprisoned than a white person. The discrepancy was attributed to "decades of racial prejudice in the criminal justice system".^[46]

In the United States, the racial profiling of minorities by law-enforcement officials has been called racial discrimination.^[47] Within the criminal justice system of the United States, minorities are convicted and imprisoned disproportionately when compared to the majority.^[48][49] As early as 1866, the Civil Rights Act and Civil Rights Act of 1871 provided a remedy for intentional racism in employment by private employers and state and local public employers. The Civil Rights Act of 1991 expanded the damages available in Title VII cases and granted Title VII plaintiffs the right to a jury trial.

Racial discrimination in hiring has been shown to exist in both the United States and Europe.^[50][51] Using a field experiment, Marianne Bertrand and Sendhil Mullainathan showed that applications from job candidates with white-sounding names received 50 percent more callbacks for interviews than those with African-American-sounding names in the United States at the start of this millennium.^[52] A 2009 study by Devah Pager, Bruce Western, and Bart Bonikowski found that black applicants to low-wage jobs were half as likely as identically qualified white applicants to receive callbacks or job offers.^[53] More recently, Stijn Baert, Bart Cockx, Niels Gheyle and Cora Vandamme replicated and extended their field experiment in Belgium, Europe. They found that racial discrimination in the labour market is heterogeneous by the labour market tightness in the occupation: compared to natives, candidates with a foreign-sounding name are equally often invited to a job interview in Belgium if they apply for occupations for which vacancies are difficult to fill, but they have to send twice as many applications for occupations for which labor market tightness is low.^[54]

Regional or geographic discrimination is discrimination based on the region in which a person lives or was born. It differs from national discrimination in that it may not be based on national borders or the country in which the victim lives, instead, it is based on prejudices against a specific region of one or more countries. Examples include discrimination against Chinese who were born in regions of the countryside that are far away from cities that are located within China, and discrimination against Americans who are from the southern or northern regions of the United States. It is often accompanied by discrimination based on accent, dialect, or cultural differences.^[55]

Religious discrimination is valuing or treating people or groups differently because of what they do or do not believe or because of their feelings towards a given religion. For instance, the indigenous Christian population of the Balkans, known as the "rayah" or the "protected flock", was subjected to discrimination under the Ottoman Kanun–i–Rayah. The word is sometimes translated as 'cattle' rather than 'flock' or 'subjects' in order to emphasize the Christian population's inferior status to that of the Muslim rayah.^[56]

Restrictions upon Jewish occupations were imposed by Christian authorities. Local rulers and church officials closed many professions to religious Jews, pushing them into marginal roles considered socially inferior, such as tax and rent collecting and moneylending, occupations only tolerated as a "necessary evil".^[57] The number of Jews who were permitted to reside in different places was limited; they were concentrated in ghettos and were not allowed to own land. In Saudi Arabia, non-Muslims are not allowed to practice their religion publicly and they cannot enter Mecca and Medina.^[58][59] Furthermore, private non-Muslim religious gatherings might be raided by the religious police.^[59]

In a 1979 consultation on the issue, the United States commission on civil rights defined religious discrimination in relation to the civil rights which are guaranteed by the Fourteenth Amendment to the United States Constitution. Whereas religious civil liberties, such as the right to hold or not to hold a religious belief, are essential for Freedom of Religion (in the United States secured by the First Amendment), religious discrimination occurs when someone is denied "equal protection under the law, equality of status under the law, equal treatment in the administration of justice, and equality of opportunity and access to employment, education, housing, public services and facilities, and public accommodation because of their exercise of their right to religious freedom".^[60]

Though gender discrimination and sexism refer to beliefs and attitudes in relation to the gender of a person, such beliefs and attitudes are of a social nature and do not, normally, carry any legal consequences. Sex discrimination, on the other hand, may have legal consequences. Though what constitutes sex discrimination varies between countries, the essence is that it is an adverse action taken by one person against another person that would not have occurred had the person been of another sex. Discrimination of that nature is considered a form of prejudice and in certain enumerated circumstances is illegal in many countries.

Sexual discrimination can arise in different contexts. For instance, an employee may be discriminated against by being asked discriminatory questions during a job interview, or by an employer not hiring or promoting, unequally paying, or wrongfully terminating, an employee based on their gender.

Sexual discrimination can also arise when the dominant group holds a bias against the minority group. One such example is Wikipedia. In the Wikipedian community, around 13 percent of registered users are women.^[62] This creates gender imbalances, and leaves room for systemic bias. Women are not only more harshly scrutinized, but the representation of women authors are also overlooked. Relative to men, across all source lists, women have a 2.6 greater odds of omission in Wikipedia.^[63] In an educational setting, there could be claims that a student was excluded from an educational institution, program, opportunity, loan, student group, or scholarship because of their gender. In the housing setting, there could be claims that a person was refused negotiations on seeking a house, contracting/leasing a house or getting a loan based on their gender. Another setting where there have been claims of gender discrimination is banking; for example if one is refused credit or is offered unequal loan terms based on one's gender.^[64] As with other forms of unlawful discrimination, there are two types of sex discrimination – direct discrimination and indirect discrimination. Direct sex discrimination is fairly easy to spot – 'Barmaid wanted', but indirect sex discrimination, where an unnecessary requirement puts one sex at a disproportionate disadvantage compared to the opposite sex, is sometimes less easy to spot, although some are obvious – 'Bar person wanted – must look good in a mini skirt'.^[65] Another setting where there is usually gender discrimination is when one is refused to extend their credit, refused approval of credit/loan process, and if there is a burden of unequal loan terms based on one's gender. Socially, sexual differences have been used to justify different roles for men and women, in some cases giving rise to claims of primary and secondary roles. While there are alleged non-physical differences between men and women, major reviews of the academic literature on gender difference find only a tiny minority of characteristics where there are consistent psychological differences between men and women, and these relate directly to experiences grounded in biological difference.^[66]

Unfair discrimination usually follows the gender stereotyping held by a society.^[68]

The United Nations had concluded that women often experience a "glass ceiling" and that there are no societies in which women enjoy the same opportunities as men.^[69] The term "glass ceiling" is used to describe a perceived barrier to advancement in employment based on discrimination, especially sex discrimination.^[70] In the United States in 1995, the Glass Ceiling Commission, a government-funded group, stated: "Over half of all Master's degrees are now awarded to women, yet 95% of senior-level managers, of the top Fortune 1000 industrial and 500 service companies are men. Of them, 97% are white." In its report, it recommended affirmative action, which is the consideration of an employee's gender and race in hiring and promotion decisions, as a means to end this form of discrimination.^[71] As of 2010, women accounted for 51% of workers in high-paying management, professional, and related occupations. They outnumbered men in such occupations as public relations managers, financial managers, and human resource managers.^[72]

In addition, women are found to experience a sticky floor. While a glass ceiling implies that women are less like to reach the top of the job ladder, a sticky floor is defined as the pattern that women are, compared to men, less likely to start to climb the job ladder. A sticky floor is related to gender differences at the bottom of the wage distribution. It might be explained by both employer discrimination and gender differences in career aspirations.^[73]

Intersex persons experience discrimination due to innate, atypical sex characteristics. Multiple jurisdictions now protect individuals on grounds of intersex status or sex characteristics. South Africa was the first country to explicitly add intersex to legislation, as part of the attribute of 'sex'.^[74] Australia was the first country to add an independent attribute, of 'intersex status'.^[75][76] Malta was the first to adopt a broader framework of 'sex characteristics', through legislation that also ended modifications to the sex characteristics of minors undertaken for social and cultural reasons.^[77][78]

Transgender individuals, whether male-to-female, female-to-male, or genderqueer, often experience transphobic problems that often lead to dismissals, underachievement, difficulty in finding a job, social isolation, and, occasionally, violent attacks against them.

Nevertheless, the problem of gender discrimination does not stop at transgender individuals or with women. Men are often the victim in certain areas of employment as men begin to seek work in office and childcare settings traditionally perceived as "women's jobs". One such situation seems to be evident in a recent case concerning alleged YMCA discrimination and a Federal Court Case in Texas.^[79] The case actually involves alleged discrimination against both men and black people in childcare, even when they pass the same strict background tests and other standards of employment. It is currently being contended in federal court, as of fall 2009.

Discrimination in slasher films is relevant. Gloria Cowan had a research group study on 57 different slasher films. Their results showed that the non-surviving females were more frequently sexual than the surviving females and the non-surviving males. Surviving as a female slasher victim was strongly associated with the absence of sexual behavior. In slasher films, the message appears to be that sexual women get killed and only the pure women survive, thus reinforcing the idea that female sexuality can be costly.^[80]

One's sexual orientation is a "predilection for homosexuality, heterosexuality, or bisexuality".^[81] Like most minority groups, homosexuals and bisexuals are vulnerable to prejudice and discrimination from the majority group. They may experience hatred from others because of their sexual preferences; a term for such hatred based upon one's sexual orientation is often called homophobia. Many continue to hold negative feelings towards those with non-heterosexual orientations and will discriminate against people who have them or are thought to have them. People of other uncommon sexual orientations also experience discrimination. One study found its sample of heterosexuals to be more prejudiced against asexuals than to homosexuals or bisexuals.^[82]

Employment discrimination based on sexual orientation varies by country. Revealing a lesbian sexual orientation (by means of mentioning an engagement in a rainbow organisation or by mentioning one's partner name) lowers employment opportunities in Cyprus and Greece but overall, it has no negative effect in Sweden and Belgium.^{[83][84][85][86]} In the latter country, even a positive effect of revealing a lesbian sexual orientation is found for women at their fertile ages.

Besides these academic studies, in 2009, ILGA published a report based on research carried out by Daniel Ottosson at Södertörn University College, Stockholm, Sweden. This research found that of the 80 countries around the world that continue to consider homosexuality illegal, five carry the death penalty for homosexual activity, and two do in some regions of the country.^[87] In the report, this is described as "State sponsored homophobia".^[88] This happens in Islamic states, or in two cases regions under Islamic authority.^[89][90] On February 5, 2005, the IRIN issued a reported titled "Iraq: Male homosexuality still a taboo". The article stated, among other things that honor killings by Iraqis against a gay family member are common and given some legal protection.^[91] In August 2009, Human Rights Watch published an extensive report detailing torture of men accused of being gay in Iraq, including the blocking of men's anuses with glue and then giving the men laxatives.^[92] Although gay marriage has been legal in South Africa since 2006, same-sex unions are often condemned as "un-African".^[93] Research conducted in 2009 shows 86% of black lesbians from the Western Cape live in fear of sexual assault.^[94]

A number of countries, especially those in the Western world, have passed measures to alleviate discrimination against sexual minorities, including laws against anti-gay hate crimes and workplace discrimination. Some have also legalized same-sex marriage or civil unions in order to grant same-sex couples the same protections and benefits as opposite-sex couples. In 2011, the United Nations passed its first resolution recognizing LGBT rights.

Drug use discrimination is the unequal treatment people experience because of the drugs they use.^[95] People who use or have used illicit drugs may face discrimination in employment, welfare, housing, child custody, and travel,^{[96][97][98][99]} in addition to imprisonment, asset forfeiture, and in some cases forced labor, torture, and execution.^[100][101] Though often prejudicially stereotyped as deviants and misfits, most drug users are well-adjusted and productive members of society.^[102][103] Drug prohibitions may have been partly motivated by racism and other prejudice against minorities,^{[104][105][106]} and racial disparities have been found to exist in the enforcement and prosecution of drug laws.^{[107][108][109]} Discrimination due to illicit drug use was the most commonly reported type of discrimination among Blacks and Latinos in a 2003 study of minority drug users in New York City, double to triple that due to race.^[110] People who use legal drugs such as tobacco and prescription medications may also face discrimination.^{[111][112][113]}

Ideas of self-ownership and cognitive liberty affirm rights to use drugs, whether for medicine^{[114][115][116]} recreation,^{[117][118][119]} or spiritual fulfilment.^{[120][121][122]} Those espousing such ideas question the legality of drug prohibition and cite the rights and freedoms enshrined in such documents as the U.S. Declaration of Independence, the U.S. Constitution and Bill of Rights,^[123][124] the European Convention on Human Rights,^[125][126] and the Universal Declaration of Human Rights,^[127] as protecting personal drug choices. They are inspired by and see themselves following in the tradition of those who have struggled against other forms of discrimination in the past.^[128]

Drug policy reform organizations such as the Drug Policy Alliance,^[129] the Drug Equality Alliance,^[130] the Transform Drug Policy Foundation,^[131] and the Beckley Foundation^[132] have highlighted the issue of stigma and discrimination in drug policy. The Partnership for Drug-Free Kids also recognizes this issue^[133] and shares on its website stories that "break through the stigma and discrimination that people with drug or drinking problems often face."^[134]

A report issued by the Global Commission on Drug Policy, critical of the global war on drugs,^[135] states, under "Undermining Human Rights, Fostering Discrimination":

Although still illegal at the federal level, about half of U.S. states have legalized marijuana for medical use and several of those states have laws, or are considering legislation, specifically protecting medical marijuana patients from discrimination in such areas as education, employment, housing, child custody, and organ transplantation.^{[137][138][139]}

In the US, a government policy known as affirmative action was instituted to encourage employers and universities to seek out and accept groups such as African Americans and women, who have been subject to discrimination for a long time.^[140]

Some attempts at antidiscrimination have been criticized as reverse discrimination. In particular, minority quotas (for example, affirmative action) may discriminate against members of a dominant or majority group or other minority groups. In its opposition to race preferences, the American Civil Rights Institute's Ward Connerly stated, "There is nothing positive, affirmative, or equal about 'affirmative action' programs that give preference to some groups based on race."^[141]

Australia

Canada

Hong Kong

Israel

Netherlands

United Kingdom

United States

Important UN documents addressing discrimination include:

Social theories such as egalitarianism assert that social equality should prevail. In some societies, including most developed countries, each individual's civil rights include the right to be free from government sponsored social discrimination.^[155] Due to a belief in the capacity to perceive pain or suffering shared by all animals, "abolitionist" or "vegan" egalitarianism maintains that the interests of every individual (regardless its species), warrant equal consideration with the interests of humans, and that not doing so is "speciesist".^[156]

Discrimination, in labeling theory, takes form as mental categorization of minorities and the use of stereotype. This theory describes difference as deviance from the norm, which results in internal devaluation and social stigma^[157] that may be seen as discrimination. It is started by describing a "natural" social order. It is distinguished between the fundamental principle of fascism and social democracy. The Nazis in 1930s-era Germany and the pre-1990 Apartheid government of South Africa used racially discriminatory agendas for their political ends. This practice continues with some present day governments.^[158]

Economist Yanis Varoufakis (2013) argues that "discrimination based on utterly arbitrary characteristics evolves quickly and systematically in the experimental laboratory", and that neither classical game theory nor neoclassical economics can explain this.^[159] Varoufakis and Shaun Hargreaves-Heap (2002) ran an experiment where volunteers played a computer-mediated, multiround hawk-dove game (HD game). At the start of each session, each participant was assigned a color at random, either red or blue. At each round, each player learned the color assigned to his or her opponent, but nothing else about the opponent. Hargreaves-Heap and Varoufakis found that the players' behavior within a session frequently developed a discriminatory convention, giving a Nash equilibrium where players of one color (the "advantaged" color) consistently played the aggressive "hawk" strategy against players of the other, "disadvantaged" color, who played the acquiescent "dove" strategy against the advantaged color. Players of both colors used a mixed strategy when playing against players assigned the same color as their own.

The experimenters then added a cooperation option to the game, and found that disadvantaged players usually cooperated with each other, while advantaged players usually did not. They state that while the equilibria reached in the original HD game are predicted by evolutionary game theory, game theory does not explain the emergence of cooperation in the disadvantaged group. Citing earlier psychological work of Matthew Rabin, they hypothesize that a norm of differing entitlements emerges across the two groups, and that this norm could define a "fairness" equilibrium within the disadvantaged group.^[160]

It is debated as to whether or not markets discourage discrimination brought about by the state. One argument is that since discrimination restricts access to customers and incurs additional expense, market logic will punish discrimination. Opposition by companies to "Jim Crow" segregation laws is an example of this.^[161] An alternative argument is that markets don't necessarily undermine discrimination, as it is argued that if discrimination is profitable by catering to the "tastes" of individuals (which is the point of the market), then the market will not punish discrimination. It is argued that microeconomic analysis of discrimination uses unusual methods to determine its effects (using explicit treatment of production functions) and that the very existence of discrimination in employment (defined as wages which differ from marginal product of the discriminated employees) in the long run contradicts claims that the market will function well and punish discrimination.^[162][163]