In article three realities in which their lives the person — empirical, sociocultural and existential are analyzed. Each matched the reality of social knowledge domains with which they are described — the moral, conventional, and personal. It is proved that realities are understood by people on types of understanding-knowledge, understanding-interpretation and understanding-comprehension. It is shown that the person at the same time exists in different realities, understands them on the unequal psychological bases and uses various types of social knowledge for the description.