A system in which people are ranked strictly according to individual ability and performance is known as an open class society. An open system implies that the position of each individual is influenced by the person achieved status. In an open class system, competition among members of society is encouraged .In contrast to this, a system in which status is theoretically based strictly on heredity, is known as a closed class society. Caste provides an example of closed class society or stratification system. An individual automatically belongs to the caste of his parent and, except in rare instances, spends the rest of his life in that status (now some changes are occurring in this situation.. By comparison with class system (which is known as open system of stratification), the rate of mobility in caste system is altogether absent. In this system, there is little or no possibility of individual mobility. In such societies, social placement is based on ascribed characteristics, such as caste, race or family background, which cannot easily be changed. No class system or stratification system is entirely open or closed. Modern industrial societies tend towards the open class system, while traditional agricultural societies often had caste or estate systems, which restricted social mobility. Negro-white relationship in America are often cited as a caste situation although the class differences within each caste make the caste- class concept and designation more useful because it