A society is composed out of a number of individuals who interact with each other, in order to interact with each other they must form common interpretations of their perceptions (if they perceive things differently they can’t interact), as they perceive a common reality they will a form a common method of deriving their needs from it as humans generally have the same needs, the common method is what we call culture.
Culture - A set of values, norms and social institutions that a population shares and is transitioning to the next generation through social learning.
The family unit - The main means by which social learning is perpetuated.