Density-independent factors are forces that affect the size of a population of living things regardless of the density of the population. These factors are typically physical or abiotic factors of the environment, unrelated to the size of the population in question. Examples of density-independent factors include natural disasters like wildfires, pollution, climate extremes, and other environmental stressors. These factors can affect a population of living things whether individuals are clustered close together or spaced far apart.

Density-independent factors are different from density-dependent factors, which are biotic or living organism-related factors that emerge when the concentrations of individuals in a population rise above a certain level. Density-dependent factors include competition for limited resources, predation, and diseases.

In summary, density-independent factors are physical or abiotic factors that affect the size of a population of living things regardless of the density of the population, while density-dependent factors are biotic or living organism-related factors that emerge when the concentrations of individuals in a population rise above a certain level.