Population growth is limited by environmental factors, which contribute to the carrying capacity of a population. There are two broad types of these limiting factors: density-dependent and density-independent.

Density-dependent factors will inhibit the growth rate, by increasing the death rate or decreasing the birth rate, based on the population density. An example of this is with limited resources: as the population density increases, food may become more scarce, increasing competition and limiting the population. Factors such as territory, water, food, light, etc. are examples of density-dependent factors. As infectious diseases experience increased transmission with higher population density, they too are a density-dependent factor.

Density-independent factors will change the birth and death rates, but they will not change with the population density. An example of this could be a drought, which would limit the population regardless of its size. Such factors are typically abiotic and include things such as natural disasters, pollutants, and climate.