The document defines and discusses several key demographic terms including: - Population density, which measures the number of people per square mile in an area. - Population growth, which measures the percent change in a population each year. - Birth rate, which measures the average number of children a woman will have. - Infant mortality rate, which measures the number of babies that die before their first birthday per 1,000 births. - Life expectancy, which measures the average lifespan of people in an area, usually separated by gender.