Differentiation is the law of nature. It is true in the case of human society. Human society is not homogeneous but heterogeneous. Men differ from one another in many respects.
There are two main theories concerning the origin of social stratification. (i) Theory of economic determinism of Karl Marx, which is often referred to as the conflict theory and (ii) The functionalist theory. They are stated below.
The glimpse of the cultures of the world reveals that no society is 'classless', that is, unstratified. All the known established societies of the world are stratified in one way or the other.