On Earth there is a big variety of ethnic groups and a bigger number of ethnic groups, each of which is in own way unique and is of interest to ethnographers.
Concept
The ethnic group is a community of people. However this term can be used more, than in one value. Most often the term is used concerning subethnic group (subethnic group), i.e. the group of any ethnic group having besides ethnic, by own subethnic consciousness and the name. Also it can be the group of ethnic group isolated from it territorially owing to some circumstances, for example, of migration processes.
Sometimes the term "ethnic group" is used concerning the group of ethnic groups having related origin and similar culture. But more often in this case the term "metaethnic community" is applied.
Sometimes also the concept "ethnic group" is used in ethnic group value, however the last nevertheless is a concept of higher rank. Representatives of ethnic group have the general origin, the territory of accommodation, culture, language, consciousness, etc. In translation from Greek the ethnic group is the people. Thus, ethnic (or subethnic) the group is the community of the people belonging to any people / ethnic group, which at the same time is compactly living, having the cultural features and realizing them and also having own self-name. Members of ethnic group belong at the same time to subethnic group and to ethnic group as to more global community. For example, Digors are a subethnic group of the Ossetian people, and a nagaybaka - Tatar.
Emergence of ethnic groups
Ethnic groups can result from territorial office of a part of ethnic group, incomplete assimilation, a special social status of group, differences of the religious plan, etc. Subetnos can exist as confessional community, as estate and as the ethnographic group living in the isolated territory. Subethnic group, recognizing belonging to larger ethnic group, nevertheless, has some differences in behavior and culture, characteristics and feeling of closer unity and solidarity in the ethnic group. Criteria by which it is allocated can be objective and subjective. For example, differences can consist in language, religion, economic specialization, geographical origin, anthropological type, the eaten food and clothes, etc. There are various ethnological theories concerning determination of ethnicity. Some experts consider that the ethnic group is distinguished by objective signs, and others - that ethnic groups and subethnic groups - rather historically arisen social communities.