A caste is a fixed social group into which an individual is born within a particular system of social stratification: a caste system. Within such a system, individuals are expected to marry exclusively within the same caste (endogamy), follow lifestyles often linked to a particular occupation, hold a ritual status observed within a hierarchy, and interact with others based on cultural notions of exclusion, with certain castes considered as either more pure or more polluted than others. The term "caste" is also applied to morphological groupings in eusocial insects such as ants, bees, and termites.
