The paper offers a detailed overview of basic terms and definitions related to population and demography, alongside the subject of the research related to demographical trends that are currently popular in the Republic of Croatia. The objective of this paper is to bring this topic closer as one of the essential foundations of the state and society, i.e. to present all of its importance and purpose for which it exists in that sense. Basic definitions and theoretical descriptions of the concepts and the structure of the population are provided at the beginning of the paper in a way that the definitions of the concepts of population, demography and factors of population and demographic change are simplified. In addition to the above mentioned basic concepts, the population and its changes are further structured in the paper, through the processing of titles where the movement and development of the population of the Republic of Croatia is shown in detail, from its beginnings to the present day. This is shown best through concrete research, analysis of the demographic trends and movements of Croatian population. The last title of the paper, population policy, offers possible solutions and steps which should be taken in the future, and which show the attitude of the state towards the subject of the policy. The topic of the paper confirms the role the population has in the economic policy of the state as one of the elements, i.e. factors that economic policy has an impact on, because it is this scientific discipline that guarantees the bare minimum of existence and prosperity.