The number of people living in a defined area is its population. Demographers track total counts, growth rates, and composition by age, sex, and other characteristics. Censuses and surveys provide the basic data.

World population has grown rapidly since the industrial era, though growth rates now vary widely between regions. Some countries face aging and potential decline; others still experience rapid increase. Population size interacts with resources, technology, and institutions to shape development outcomes.

Distribution is highly uneven—most people live on a small fraction of the land surface. Understanding population dynamics is fundamental to planning for food, water, energy, and urban infrastructure. The figures themselves are constantly updated as births, deaths, and migration continue.

• Total number of people in an area
• Tracked by censuses and surveys
• Varies in growth rate and age structure
• Unevenly distributed across the globe