Europeans are the focus of European ethnology, the field of anthropology related to the various ethnic groups that reside in the states of Europe. Groups may be defined by common ancestry, language, faith, historical continuity, etc. There are no universally accepted and precise definitions of the terms "ethnic group" and "nationality", but in the context of European ethnography in particular, the terms ethnic group, people, nationality and ethno-linguistic group are used as mostly synonymous. Preference may vary in usage with respect to the situation specific to the individual countries of Europe, and the context in which they may be classified by those terms.