Ethnic group is a group of people with characteristics in common that distinguish them from most other people of the same society. Members may have ties of ancestry, culture, language, nationality, or religion, or a combination of these things.
Most ethnic groups are minority groups with at least some values or institutions that differ from those of the larger society. Since ancient times, ethnic groups have resulted from migrations, wars, slavery, changed political boundaries, and other major movements of peoples.
In some countries, ethnic identification may affect both social standing and access to power. In Japan, for example, people of Korean ancestry have suffered discrimination by people of Japanese ancestry.
In the United States, the term ethnic group refers especially to nationality groups that have immigrated to America since about 1840. These groups include Chinese, Dutch, German, Greek, Irish, Italian, Japanese, Jewish, Mexican, and Polish people. Other groups include African Americans, whose ancestors were brought to the United States and enslaved, and Indigenous (native) people.
Ethnic groups provide their members with a sense of belonging. They can bring variety and richness to a society by introducing their own ideas and ways of life. Some members of ethnic groups prefer to live with members of their own group. But ethnic groups that promote their own interests above those of others in a multiethnic country can threaten national unity. In many parts of the world, neighboring ethnic groups dislike and distrust one another. 
The United States is one of the most ethnically mixed societies in the world. Some social scientists call the nation a melting pot, meaning its many different ethnic groups have joined to form a unified culture and have given up their ethnic ties. Others think the country consists of many separate ethnic groups. Their view is called ethnic pluralism. Most social scientists think that there has been considerable “melting” in the United States, but that the nation also reflects much pluralism.
See the People section of the various continent and country articles in World Book such as Africa (People).
