It is the living together of rational and free human beings cooperating in a steady way common good-oriented. Man is naturally sociable. There are three types of society: the domestic one, established by family; civil society, that gathers families founding the State; and religious society, a community of believers.
Man has always been living in society. Aristotle said that man is a political animal, i. e., is living in a “polis” or a city founding the society.
J.J. Rousseau denied that society is natural and healthy for man. He defended the man to be originally good, but he was corrupted living in society. These theories, not proven by experience, are widely rejected.
Although human society is not perfect, that is due to some men not looking for common good, but their particular one and so become corrupts. It is the individual who gives society their own wickedness.