Aging population - A condition that exists when crude birth rates and death rate decline significantly, leading to an inverted population pyramid, an older dependency ratio, and social welfare related to care of the elderly.

Agricultural Density - Total number of farmers divided by arable land.

Anti-natalist policies - Social, economic, or political measures that incentivize a reduction in birth rates

Arithmetic Density - Total number of people divided by total land area.

Asylum Seekers - A person who has fled their home country as a refugee and who seeks sanctuary

Boserup Theory - Population change (growth) drives the intensification of agricultural production; counters Malthusian theory.

Carrying Capacity – The number of people or crop that a region can support without environmental degradation

Chain Migration - The flow of clusters of individuals from a common place of origin to similar destinations in a new location.

Climate - Average measures of temperature, wind, humidity, snowfall, rainfall, etc. in a location over the course of many years.

Contraception(contraceptive) - medication or devices used for pregnancy prevention or for health benefits unrelated to sexual activity, like cancer prevention, acne control, and improvements in menstrual cramps and bleeding.

Crude Birth Rate - The number of births per year per 1000 population.

Crude Death Rate - The number of deaths per year per 1000 population.

Culture - Shared or learned behaviors of a group of people related to the immaterial (beliefs, values, knowledge, etc.) and material objects and possessions.

Demographic Transition Model - A four stage theory of population change that occurs over time in societies as these societies experience variations in levels of development, urbanization, industrialization, and other factors.

Demography - The study of the size, composition, and geographic distribution of human populations and how population changes due to fertility, mortality, and migration.  

Dependency Ratio - The proportion of non-working aged individuals who draw upon social welfare and public services without contributions through income and other taxes. For example: the young will draw upon public funding for items like schools, while elderly will draw upon pension funding and high demands for health care.

Economics – A social science concerned with the study of human behavior related to material well-being, wealth, and decision making related to scarcity of resources. 

Epidemiological Transition Model-Theory that studies the complex changes in patterns of health and disease and the interaction of these patterns on demographic, economic, and sociologic determinants and consequences over time.

Erlich Theory –A Malthusian Theory presented in the 1960's that posits(assumes) that a population bomb would cause utter destruction of human population; based upon developing countries entering stage two of the demographic transition model at that time; would be expanded to include natural resources along with agricultural production.

Forced Migration - The movement of refugees and internally displaced people as well as those displaced by natural disasters, chemical or nuclear disasters, famine, or development projects.

Guest Worker(temporary foreign worker) - Migrants who enter a country legally on temporary work permits or visas generally through government programs.

Immigration Policies - Government policies aimed at increasing or decreasing certain types of immigration via use of programs (guest worker visas, student visas), quotas against certain groups, or other forms of legal measures.

Infant Mortality Rate - The number of deaths occurring in the first year of life per 1000.

Internal Migration - he permanent movement of people within a country; typically rural to urban in flow.

Internally Displaced Persons - Persons or groups of persons who have been forced or obliged to flee or to leave their homes or places of habitual residence to avoid effects of armed conflict, generalized violence, violations of human rights or natural or human-made disasters, and who have not crossed an internationally recognized state border.

Intervening Obstacles – Physical or cultural features that restrict the flow of goods and people. For example, mountains, political boundaries, major bodies of water, deserts.

Intervening Opportunities - A location that may offer a better alternative as a point of origin or destination.

Landforms - Four major site characteristics that exist in the natural landscape: plains, hills, plateaus, and mountains.

Life Expectancy - The average number of years a person would live if current mortality trends were to continue. 

Malthusian Theory - The theory that agricultural production grows in a linear fashion, while population grows exponentially, leading to a crisis event where population would outstrip the earth's ability to feed the population of an area.

Medical Care(Health Care) - Spending and quality of health related care including preventative measures like exercise, screenings, etc. and treatment types like medications and therapy. 

Migration- The expected permanent movement of a person or group of persons from one location to another.

Mortality – Concepts related to dying. (crude death rate, infant mortality rate).

Neo-Malthusian – The new Malthusians who believe that other natural resources will also be outstripped by human population growth and lead to crisis events. For example: oil, natural gas, fresh water.

Physiological Density - Total number of people divided by total arable land.

Politics - Activities associated with governance of a country and other areas related to political relations between countries, debates among groups within countries, and the study of government and the state.

Population Doubling Time –The period of time required for any beginning total (population) experiencing compounding growth to double in size.  

Population Pyramid - A graphic representation of age and sex composition of a population (usually national in scale).

Pro-natalist Policies - Social, economic, or political measures that incentivize an increase in birth rates within a country.

Pull Factors – Economic, political, or social factors that draw people to immigrate to a location.

Push Factors – Economic, political, or social factors that drive people to emigrate from a location.

Rate of Natural Increase(RNI) -The difference between births and deaths within a country; excludes immigration and emigration; can be negative.

Ravenstein’s law of Migration –  series of patterns noted through studying typical migrants: most people move a short distance, economic forces drive migration, rural people emigrate more than urban people, major cities tend to be destinations for long-distance travelers, women migrate more within countries while men migrate more internationally.

Refugees - A person residing outside his or her country of nationality, who is unable or unwilling to return because of a fear of persecution on account of race, religion, nationality, membership in a political or social group, or political opinion with clear international legal status and protection of the United Nations High Commissioner of Refugee

Rural-to-Urban Migration - The most typical flow of migration throughout all of human history

Slavery - The condition in which a group of individuals is owned by others. In historic times, led to triangle slave trade and large scale, forced migration of Africans to the Americas. In modern time, leads to trafficked people for labor and sexual exploitation.

Step Migration - Migration that occurs in stages towards a final destination.

Total Fertility Rate - The number of children who would be born per woman (or per 1000 women) if she/they were to pass through childbearing years bearing children according to current rates.

Transhumance - A form of pastoralism or nomadism in which populations move livestock seasonally between summer and winter pastures.

Transnational Migration - A more modern form of migration where individuals live in two places at once or shuttle between them regularly.

Voluntary Migration - Migration undertaken by choice

Water Bodies - The aquatic biome that includes all major forms of aquatic features like streams, rivers, aquifers, lakes, ponds, inlets, oceans, seas, etc.