The book contains six units having with most of basic concepts of population studies. Unit-I contains with Definition, Nature and scope of population studies, Components of Population change. Population structure: Need for the study of Age and Sex structure, their determinants, population pyramids. Population Size, growth and age sex structure in India. Unit-II contains Definition of basic concepts fertility period and cohort, fecundity, sub fecundity, conception, pregnancy roaster, pregnancy rate, parity, order, parity progression ratio, birth interval open and closed birth intervals, live birth, still birth, menarche, sterility, menopause and Intrinsic birth and death rates, Stable population and Measures of Fertility. Unit-III contains Definition and basic concepts of Mortality, Measures of Mortality, and Factors affecting Mortality. Unit-IV contains Concept of Mobility and Migration: Sources and quality of data; Types of migration; Types of migration in India. Lastly, Unit-V contains Measures of Internal Migration: Methods of estimation and Theories of migration.