Racism was a prevalent ideology in Europe and America in the late 19th and early 20th centuries. Racist theories about supposed physical or intellectual superiority were advanced by Arthur de Gobineau and Houston Stewart Chamberlain, both of whom insisted that supreme among the races were members of the mythical Nordic, or Aryan race.

Nazi Germany under Adolf Hitler based its extermination of millions of Jews and other "non-Aryans" on this theory of race supremacy and the corollary concept of racial purity.

As an ideology, racism has been on the wane since the 1940s, although in a few countries, such as in the case of South Africa Apartheid, it has had the support of the political leadership. In other countries it lingers on as a folk mythology.

The scientific opinion in both the social and the biological sciences, however, now rejects the notion that large human populations, such as the so-called white, black, and yellow races, behave differently because of their physical appearance. Genetic differences between population groups do exist, of course. None of these group differences, however, has yet been shown to affect personality, intelligence, or, indeed, any ability that significantly relates to social behavior.

In recent years the term racism has been at times misapplied to various related but distinct social attitudes and occurrences. For example, feelings of cultural superiority based on language, religion, morality, manners, or some other aspect of culture are sometimes labeled racist, but the proper term for such feelings is ethnocentrism.
Because humans tend to take for granted the culture they are born and raised in, the tendency toward cultural bias in favor of one's own group is universally present. Ethnocentrism thus may serve to encourage cohesion and solidarity among group members; it may also contribute to attitudes of superiority, intolerance, and even contempt for groups with different customs and lifeways. In the 19th century, for example, ethnocentrism served to reinforce colonial rule in Asia and Africa. Because European society tended to consider non-Western cultures inferior to its own, the notion evolved that it was the "white man's burden" to teach Western traditions and techniques to non-European peoples.

The causes of racism are complex and cannot be reduced to a single factor. Its rise and fall are often linked with real conflicts of interest and competition for scarce resources. Historically, racism has commonly accompanied slavery, colonialism, and other forms of exploitation and gross inequality. In other cases the insecure white working class and lower middle class of industrial societies, for example, have often expressed racist attitudes toward defenseless minorities, such as blacks in the United States or Commonwealth immigrants in Great Britain.

Rapid social change often fosters racism. Examples are the sudden immigration of highly visible groups of foreigners, quick changes in the racial composition of a neighborhood, or the threat of political change brought on by a nationalist movement.
Racism, in short, is frequently an irrational reaction to a real or perceived threat to the status quo. It can therefore suddenly flare up, as with anti-semitism in Germany in the 1930s and '40s, or remain dormant, depending on such external circumstances as economic depression and the willingness of organized groups to exploit racism for political ends.

Discrimination, in society, can be defined as the unequal treatment of equals. Discrimination may be experienced by ethnic minorities - the term ethnic encompasses race and religion as well as national and cultural traditions. Occasionally, as in South Africa, the majority group is the target of discrimination. Discrimination may also be directed at women, old people, handicapped people, and homosexuals.

There is a distinction between discrimination and prejudice. Discrimination is expressed in overt, concrete behavior, while prejudice is expressed in attitude. The person who discriminates does so because of prejudice, but this need not be the case; for example, a personnel manager may refuse to hire young people because of company policy rather than his or her own attitude.

In the contemporary United States, discrimination in employment can be especially damaging, but discrimination is also manifested in housing, education, and other areas. Ethnic discrimination in the United States is closely related to historic patterns of immigration and migration. The earlier arrivals would typically be pushed upward onto a higher economic and social level by the next wave of newcomers. Eventually, the process leads to integration, although for some groups factors such as a readily visible difference in skin color have complicated the assimilation process. The varying patterns of toleration and repression of Jews in Europe, where anti-semitism led to the most extreme form of discrimination, genocide, complicated their integration into American society.

Efforts to combat racial discrimination and racism have figured prominently in post-World War II U.S. history. The civil rights movement of the 1950s and '60s won the passage of important legislation such as the Civil Rights Acts. Progress toward integration among blacks and whites has been especially dramatic in the South.

Segregation is the opposite of integration. In a segregated society members of different races rarely, if ever, come into contact with one another as equals. All aspects of daily life are separated, and contact between the races is regulated so that one race is always in a superior position to the other. Until recently, white-imposed segregation of blacks and whites was the prevailing practice in the United States. In the North such segregation began well before the Civil War. Although never written into law, it was accomplished in informal custom, sometimes called de facto segregation. In the South, after the Civil War ended the institution of slavery, states began passing laws decreeing segregation by race. This was de jure segregation.

Societies are seldom completely segregated or completely integrated. In the United States today, for example, people of different races may work side by side but often have little contact in their private lives. Some scholars believe that increased contact between races on an equal basis will tend to reduce the suspicion and fear that underlie much racial hostility. But despite decades of efforts at desegregation, fear and hostility between the races remains a potent force in American life.
Segregation, whether de facto or de jure, is discriminatory. Not only does segregation limit opportunities, but it is an insulting and degrading practice and has been opposed by black (and many white) people since its beginnings. Challenges to segregation have taken two general forms. One form was insistence on equal treatment through integration. The other major challenge to segregation came from those who urged the establishment of independent black states or nations that would not be subservient to white people. Both these positions are represented in black communities today.

The dismantling of de jure segregation did not come about smoothly; it required considerable agitation by both blacks and whites. In the U.S. an incident in Montgomery, Alabama, in 1956 proved to be the start of one of the most important popular movements in U.S. history. Rosa Parks, a black working woman, refused to give up her seat in a bus and move to the section reserved for blacks. After the driver ordered her off the bus, the black community of Montgomery decided to boycott all public transportation. The boycott continued for months until Montgomery ended segregated seating on its buses. The protest spread to other cities and to other aspects of segregation.

Martin Luther King Jr., a young black minister who had been drawn into the struggle in Montgomery, emerged as a leader of the movement against segregation. King was by no means alone. Thousands of boycotts, demonstrations, sit-ins, and marches occurred as blacks and their sympathizers sought to overturn the laws protecting racial segregation. Even though the demonstrators were usually well disciplined and nonviolent, they often met bitter opposition. Reports and photographs of demonstrators being beaten by Southern law enforcement officers or attacked with police dogs and fire hoses had a strong impact on national opinion. The courts and the federal government began to respond to a growing popular indignation.
The passions and upheavals of the 1960s gave way to at least the appearance of calm in the 1970s and '80s. Protests became less frequent and widespread as blacks and whites alike took stock of the gains of one of the most tumultuous periods in U.S. history.

Black participation in the mainstream grew rapidly as the barriers came down. Able to vote everywhere, they turned to the ballot box in large numbers. Thousands of black elected and appointed officials now serve at all levels of government and have figured centrally in recent presidential elections. Jobs traditionally reserved for whites opened to blacks. During the 1960s and '70s the proportions of blacks in the professions and in managerial positions increased dramatically. By the mid-1980s blacks were almost proportionately represented among the ranks of white-collar workers, even though they remained significantly underrepresented among professionals and managerial personnel. Educational differences between blacks and whites have also been sharply reduced since the 1960s. The prospect of a decent job and an income roughly comparable to those of similarly educated whites is no longer simply a dream.
It turns out, though, that it has been far easier to eliminate legal segregation than to achieve social integration. Residential segregation in the North remains virtually as complete today as it was several decades ago. And while the economic prospects of educated blacks improve, the steady loss of manufacturing jobs in recent decades, combined with massive cuts in social spending that began with Ronald Reagan's presidency in 1980, have widened the unemployment gap between blacks and whites and increased the ranks of the black poor.
Poverty has been made worse by the rapid spread of highly addictive drugs like crack, a cocaine derivative. Overall, this has meant that progress toward reducing racial differences along a broad front of economic and social indicators has slowed or stopped altogether. To complicate matters, recent immigrants from Asia and Latin America now compete with blacks for jobs and business opportunities. As a result, conflicts have begun to erupt along many different racial lines.

The result has been a loss of momentum toward the goal of black/white equality. Indeed, some blacks have begun to publicly question the wisdom of integration, given the persistence of white resistance, and have turned their energy to strengthening black institutions. The weakening support for integration suggests that the dramatic gains of the past three decades may be neither permanent nor self-perpetuating.

Racial problems are not, of course, confined to the United States. In Great Britain, for instance, a growing population of blacks and Asians, most emigrating from former colonies, experiences considerable de facto segregation. Racial disturbances have become commonplace, although on a smaller scale than those of the United States in the 1960s. Demands for an end to immigration have been voiced, and race has become one of the most volatile political issues in Great Britain. Western European countries like France and Germany also have begun to encounter problems arising from the de facto segregation of North Africans and Middle Easterners who came to the West to seek jobs.

In recent years, international attention has also been focused on South Africa. Long the most thoroughly segregated society in the world, South Africa embarked in 1990 upon a dramatic series of reforms aimed at dismantling the system of segregation known as Apartheid. The fundamental laws that were the basis of apartheid were repealed, and new-born babies are no longer classified by race. Blacks are still excluded from political power, but negotiations toward a new non-racial constitution are planned. Still, at the very beginning of the present century, Du Bois wrote that "the problem of the twentieth century is the problem of the color line." Much remains to be done so that the same cannot be said of the 21st century.

Anti-Semitism has manifested itself in many ways: hostile popular sentiment; discriminatory legislation; expulsion; and, in Nazi Germany, deliberate extermination.

During the 19th century, anti-Semitism gained strength by appeals to (1) nationalistic motives, especially where a Jewish minority was strong, as in eastern Europe; and (2) racial motives, supported by pseudoscientific investigations and allegations. The theory of the French ethnologist J.A. Gobineau on the superiority of the Aryan race and the ideas of the Anglo-German political philosopher H.S. Chamberlain on racial purity, exercised a great influence on subsequent racist policies. In Germany, anti-Semitism became an organized movement during the late 19th century. Later, Nazism turned anti-Semitism into an official government policy that within a decade led to the systematic extermination of nearly 6 million Jews.

The Weimar Republic for the first time abolished all official discrimination against Jews. The republic was unpopular, however, and anti-Semitism was popular. Calculated use of anti-Semitism as an instrument was a major factor in Adolf Hitler's rise to power in 1933, whereupon the German Jews were immediately disfranchised, robbed of possessions, deprived of employment, barred from the schools, and subjected to physical violence and constant humiliation. Once World War II occupied the attention of the democracies, Hitler and his supporters attempted "the final solution," the complete extermination of the Jews. In addition to destroying so many individual lives, the Holocaust eradicated the communities of Central and Eastern Europe, which had been the chief centers of learning and piety for nearly a thousand years.

Holocaust, an Old Testament sacrificial term, is used by historians to describe the massacre of 6 million Jews by the German Nazi regime during World War II. Adolf Hitler gave top priority to removing the Jews from Germany. Between 1933 and 1938 the Nazis boycotted Jewish businesses, established quotas in Germany's professions and schools, forbade intermarriage between Jews and Gentiles, and instituted the first Concentration Camps at Oranienburg, Buchenwald, and Dachau - all of this while the rest of the world looked on. The Nazis used the assassination of Ernst vom Rath, a German legation secretary in Paris, as an excuse for Kristallnacht (the night of broken glass): on the night of Nov. 9-10, 1938, storm troopers burned 267 synagogues and arrested 20,000 people. Germany's Jews were also required to pay an atonement fine of $400 million for damage to their own property.

After World War II began in September 1939, 3 million Polish Jews were subjected to a blitzpogrom of murder and rape. Reinhard Heydrich, an aide to Heinrich Himmler, issued a ghetto decree that month, and Jews were progressively fenced off from the rest of the population. As 700,000 died of disease and starvation during the next 2 years, the Nazis toyed with the idea of deporting all Jews to Nisko, a proposed reservation in the Lublin area, or to Madagascar. When Germany attacked the USSR in June 1941, four special Einsatzgruppen (strike squads) were deployed against Soviet Jewish civilians. The worst atrocity committed by these squads occurred at the Babi Yar ravine in Kiev, where 33,771 Jews were machine-gunned. At Hitler's insistence, Heydrich chaired (January 1942) the Wannsee Conference on the Final Solution of the Jewish Question. During the next three years, Jews represented more than half of those exterminated as undesirables in concentration camps.

Methods of killing at Auschwitz and other camps included cyanide gas or carbon monoxide gas, electrocution, phenol injections, flamethrowers, and hand grenades.
Lacking weapons, weakened by disease and starvation, and isolated from the Allies (who were apparently apathetic about their fate), Jews nevertheless fiercely resisted the Nazis throughout the war. Perhaps as many as 60,000 joined the partisan units that operated from North Africa to Belorussia. Despite these efforts, when World War II ended, two-thirds of Europe's Jews had been murdered, more than had been slain in pogroms during the previous 1,800 years. The foundations of Western theology have been shaken by these horrors; in the past 25 years a vast literature has developed that attempts to reconcile God, civilization, and the gas chambers of Auschwitz.

In the United States and Western Europe, anti-Semitism waned after the defeat of Hitler and the creation of the national Jewish state of Israel. At its meeting in New Delhi in 1961, the World Council of Churches condemned anti-Semitism as incompatible with the teachings of Christ. In 1965 the Second Vatican Council formally repudiated the charge that all Jews are responsible for the death of Christ and condemned racism as un-Christian. Although anti-Semitism is officially disavowed in Communist countries, it long remained a political factor in the USSR, which sought to remove Jews from government and scientific positions and to keep them from emigrating to Israel.

Since World War II the Jews of the United States have achieved a degree of acceptance without parallel in Jewish history, and Jews play a significant role in intellectual and cultural life. The elimination of social barriers has led to a high rate of mixed marriage. During the same period there has been a growth in synagogue affiliation and support for Israel.
Recent estimates put the total number of Jews at about 14 million, of whom over 5 million reside in the United States, more than 2 million in the USSR, and over 3 million in Israel. France, Great Britain, and Argentina also have significant Jewish populations. The once-substantial communities in North Africa and the Middle East have been reduced to small fragments. Most of these Oriental Jews have settled in Israel.