AP Human Geo 2.1

The scientific study of population characteristics.
Population Concentration
Areas where groups of people gather or cluster. Two-thirds of the world's inhabitants are clustered in four regions: East Asia, South Asia, Southeast Asia, and Western Europe.
Population Cluster
The clustering of the world's population can be displayed on a cartogram, which depicts the size of countries according to population rather than land area, as in the case with most maps.
The portion of the Earth's surface occupied by permanent human settlement is called this. The areas of earth that humans consider too harsh for occupancy have diminished over time, whereas ecumene has increased.
arithmetic density
Geographers most frequently use this. It is the total number of people divided by total land area. (Measure can also be called population density) Geographers rely on this to compare conditions in different countries because the 2 pieces of information needed to calculate the measure, total population, and total land area, are easy to obtain.
physiological density
The number of people in a region supported by a unit area of arable land. The US physiological density is 172 persons per square kilometer (445 per square mile) or arable land.
agricultural density
The ratio of the number of farmers to the amount of arable land. The Netherlands has a much higher physiological density than does India, but had a much lower agricultural density.