Final answer:
A caste is a class group where membership is inherited at birth and marriage choices are limited to within the same group. Castes enforce endogamous marriages, contrasting with more flexible class systems that allow exogamous unions based on love and personal compatibility.
Step-by-step explanation:
A caste is a class group in which membership is determined at birth and marriage is restricted to members of one's own group. This system of social inequality is based on an individual's circumstances of birth, wherein people are not allowed to move out of their social group. Unlike in class systems where people can engage in exogamous marriages, marrying individuals from different social categories based on love and compatibility, a caste system dictates that individuals participate in endogamous marriages, confining their choice of spouse to within their own caste. The family unit, as a socially recognized group of individuals connected by blood, marriage, or adoption, serves as an emotional and economic unit of society, and its composition and function can vary across cultures and legal frameworks.