What does population density measure?

Population density specifically quantifies how many individuals reside in a certain area, typically expressed as the number of people per square kilometer or square mile. This measurement provides insight into how crowded or sparsely populated a region is and can impact various social, economic, and environmental factors. For instance, a higher population density may lead to increased demand for housing, services, and infrastructure, while a lower density might indicate more open space or rural settings.

The other options represent different concepts that do not pertain to the definition of population density. For example, resources pertain to the availability of materials and services in a given area, age distribution focuses on the demographic breakdown of a population across various age groups, and the unemployment rate measures the percentage of the labor force that is without work. Each of these aspects provides important information about a population or an economy but does not describe the density of people in a specific area.