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**Glossary**

**Demography:** the study of populations (human, non-human lifeforms, and certain objects, like cars or light bulbs)

**Quantitative data:** information that can be expressed numerically, often represented visually with graphs, tables, charts, and histograms

**Mathematical models:** computational models based on various quantitative data inputs that generate predictions about future events

**Exponential growth:** development at an increasingly rapid rate in proportion to the growing total number or size

**Columbian Exchange:** the exchange of diseases, ideas, food crops, and populations between the New World and the Old World following the voyage to the Americas by Christopher Columbus in 1492

**Replacement level fertility:** when the population replaces itself 1:1 from one generation to the next (2.1 children per woman for humans)

**Fertility rate:** the average amount of children had by women in a given population

**Population pyramid:** a graphical illustration used by demographers to show the age distribution in a population

**Urbanization:** the trend for human populations to increase disproportionately in cities

**Arable land:** land suitable for the cultivation of crops