Abstract. The number of the human population had reunited both in its quantitative side, and, especially, in the qualitative one, the most significant aspects of the various and detailed human evolution and dynamic. This demographic and synthetic indicator allowed a detailed and original process of population segmentation in the field of the contemporary analysis. Referring to a new process of demographic evolution and defining the population’s decline, demographers like Ehrlich and Longman have used the concept of demographic explosion but with the opposite demographic implosion too. World population through the accomplishment of the United Nations Population Revision or UNO prognosis seems to be forever somewhere between the limits of explosion and implosion.

Keywords: average number of population; equilibrium; demographical phenomenon; demographical event and method; cohorta; explosion and implosion; world migrant stock; registered and estimated number of population.