Ethnicity is the conscious and imaginative construction and mobilization of differences.
Ethnicity is a categorical ascription which classifies individuals in terms of their basic, most general identity.
Ethnicity is, in a globalized world, faced with the paradox that primordial (or 'locality' in the form of language or skin color, etc,) have in essence become portable.
Ethnicity is the expressive processes of cultural identification. To be contrasted with racial identity which is the repressive processes of social exclusion.
Ethnicity is social, not cultural, meaning it is determined not by behavior but by self-acknowledgement. It makes no difference whatsoever how dissimilar members may be in their overt behaviour as long as they declare that they are 'a' or 'b'.
Ethnicity is often not result from ethnic groups' own choices and preference, but rather as a response to their subordinated position in relation to the dominant.
Ethnicity is a feature of social organization rather than a nebulous expression of culture. It is the interactive delineation of boundaries rather than 'the cultural stuff' that they enclose that defines ethnic groups.