Final answer:
Population density is the measure of individuals in a given unit of area or volume, and it can significantly affect the interactions within a population, including health and survival dynamics.
Step-by-step explanation:
Population density is the average number of individuals in a population per unit of area or volume. For instance, if we have a population of 100 insects in an area of 100 square meters, the population density would be 1 insect per square meter. However, if the same population were located in just 1 square meter, the density would dramatically increase to 100 insects per square meter, indicating a much more crowded situation. Crowding can impact populations in various ways; for example, it might increase competition for resources like food and space, which can alter the health and survival of the population. Factors like these are why population density and distribution are critical for understanding population ecology.