As it can be deduced, the territorial distribution of the world population is quite unequal, since there are concentrative areas of great population agglomerations and other areas that are practically depopulated.

AChina is, at national scale, the first most populated country (nearly 1350 million inhabitants), India is the second one (about 150 million less) and United States of America is the third one (309 million inhabitants).

In relative terms, the population density is the indicator for the population distribution accordingly to the area it occupies. The usual unit for measuring the density is inhabitants/km2.

However, the population density by countries usually gives a false image of the population distribution on the earth’s surface, since some huge countries (as China, Brazil, United States, Canada and others) have extremely high populated areas next to very low populated ones. Therefore, the highest populated countries or regions are very small; sometimes city-states (as Macau, a special administrative region of China; Singapore; Hong Kong, another Chinese SAR; Monaco, a small principality; and some Lesser Antilles islands). On the other hand, Bangladesh, India and Japan, for instance, have the densest highest absolute population. Other standing out countries can be found in the American continent: Puerto Rico, El Salvador, Guatemala and Cuba.