The demographic estimates and projections found in the International Data Base are the result of over 30 years of analysis of census, survey, vital statistics, and other data by Census Bureau demographers. The IDB differs from some other online resources in several ways. First, the estimates and projections of vital rates, vital events, and midyear population presented are based on careful evaluation of census and survey results and, in part because of this evaluation process and associated estimation processes, represent a set of consistent estimates and projections of population, fertility, mortality, and international migration. The IDB is not simply a compilation of estimates taken from other sources. Second, estimates from original sources are accurately dated, and derived estimates of fertility and mortality available from the IDB reflect that dating. Third, the projections are generated using the Census Bureau's Rural/Urban Projection (RUP) program, which projects population, by single years of age, for each calendar year beyond a base year. This means IDB fertility and mortality estimates pertain to specific years rather than being average values for 5-year periods. It also means that the impact of natural disasters, civil conflicts, and changes in the health climate in a country can be reflected in year-specific estimates of fertility, mortality, and migration found in the IDB. Finally, the data are accessible in multiple ways to meet different user needs.