What is migration defined as?

Migration is defined as the movement of a population from one area to another. This process can occur for various reasons, including economic opportunities, environmental factors, social or political conditions, or disasters. The focus of migration is on the movement itself, whether it involves individuals or groups relocating temporarily or permanently, and can encompass both emigration (leaving one place) and immigration (arriving in a new place). Understanding migration is important in fields like sociology, demography, and geography because it affects population dynamics and can have significant social, economic, and cultural impacts on both the area of departure and the area of arrival. The other options provided relate to demographic aspects like birth rates and aging, but they do not encapsulate the essence of migration as a movement phenomenon.