Today in human geography we review the note we learn before.
We talked about immigration, emigration and TFR(Total Fertility Rate). TFR is average number of children born per woman. For a population to remain the same, the TFR must be 2.1. If a country's TFR higher than 2.1, the population rises. If a country's TFR lower than 2.1, the population falls.
There are two forces can make people migrate: push forces and pull forces. Push forces is the forces which coerce people to migration. Pull forces is the forces which attract people to migration.