Final answer:
Demographic Transition Theory describes the pattern of declining birth and death rates as a society advances from a pre-industrial to an industrial economy, leading to a stable or shrinking population size.
Step-by-step explanation:
The Demographic Transition Theory posits that as a society progresses from a pre-industrial to an industrialized economic system, there are marked changes in birth and death rates. During the early stages of the demographic transition, both birth rates and death rates are high. As the society develops economically and improves in medical and resource conditions, death rates begin to fall. Subsequently, with the attainment of a fully developed economy, birth rates decline and eventually stabilize at a low level, broadly matching the low death rates.
In the context of the theory, the demographic transition involves multiple stages. Initially, a fall in death rates leads to a rapid population increase. Following this surge, birth rates begin to fall as the society embraces changes such as technological advances, enhanced education, and higher living standards. The eventual equilibrium of low birth and death rates leads to modest or even negative population growth, as has been observed in countries like Japan and some European nations. The United States is also slowly transitioning to this stage.
In summary, demographic transition is a multistage model which reflects a country's transition through changes in population growth as it undergoes industrialization, shifting from high to low birth and death rates.