Since the time of the ancient Greeks, both the theory and the practice of democracy have undergone profound changes, many of which have concerned the prevailing answers to questions 1 through 3 above. Thus, for thousands of years the kind of association in which democracy was practiced, the tribe or the city-state, was small enough to be suitable for some form of democracy by the assembly, or "direct democracy."
This book with pictures and a bibliography for further reading will show you everything about the democratic institution at that time
In today's modern world every political regime, even the most authoritarian or repressive, describes itself as a democracy or a Democratic People's Republic. The concept of rule by the people, on behalf of the people, has come to be accepted as the norm, and very few would overtly espouse the cause of dictatorship, absolute monarchy, or oligarchy as the most desirable political system upon which to base the government of any country.