Population data are essential for understanding the size, distribution, composition, growth, and characteristics of people across the world. In Population and Settlement Geography, accurate population data help geographers analyze demographic trends, population distribution, migration, urbanization, and resource planning. Various sources of population data have been developed by different countries and international organizations to ensure reliable demographic information. The major sources of population data include population census, vital registration systems, sample surveys, and population registers. The population census is the most important and comprehensive source of population data. A census is the complete enumeration of all individuals living within a country at a specified time. It is generally conducted every ten years in most countries. The census provides detailed information on population size, age, sex, marital status, literacy, education, occupation, religion, language, housing conditions, migration, and household characteristics. Since every individual is counted, census data offer highly reliable information for planning economic development, public services, infrastructure, and electoral representation. However, conducting a census requires enormous financial resources, trained personnel, and efficient administration. Errors such as undercounting, overcounting, and delayed publication may also reduce its effectiveness. Vital registration systems constitute another important source of population data. These systems continuously record vital events such as births, deaths, marriages, divorces, and sometimes migration. Unlike the census, which is periodic, vital registration provides continuous demographic information