Core terms
| Term | Meaning |
|---|---|
| Population | The number of people in a place at a given time. |
| Fertility | How many children people have, often measured as children per woman. |
| Mortality | Death patterns in a population, often measured by death rates or life tables. |
| Life expectancy | The average expected years of life under current mortality patterns. |
| Migration | Movement into and out of a place. |
| Age structure | How many people are children, working-age adults or older people. |
| Projection | A model of possible future population based on assumptions. |
Why demography matters
Demography affects schools, pensions, housing, health care, cities, labor markets, climate pressure, migration and political representation. It explains not only how many people live somewhere, but what age and life-stage structure societies have.
Why projections are not predictions
A projection depends on assumptions. If fertility, mortality or migration changes, the future path changes too. Good demographic analysis therefore compares scenarios rather than pretending to know the future exactly.
Related topics
FAQ
Is demography only about population size?
No. It also studies age, births, deaths, migration, households and future scenarios.
Are projections exact?
No. They are model-based scenarios built from assumptions.