The Human Mortality Database (HMD) was created to provide detailed mortality and population data to researchers, students, journalists, policy analysts, and others interested in the history of human longevity. It is an outgrowth of the earlier Berkeley Mortality Database (BMD) and is co-sponsored by UC Berkeley (with funding from the NIA) and the Max Planck Institute for Demographic Research located in Rostock, Germany. The HMD currently provides detailed population and mortality data for 37 countries or areas. The Human Mortality Database (HMD) contains original calculations of death rates and life tables for national populations (countries or areas) as well as the input data used in constructing those tables. The input data consist of death counts from vital statistics plus census counts birth counts and population estimates from various sources. The HMD continues to add new data series to this collection. However, the database is limited by design to populations where death registration and census data are virtually complete since this type of information is required for the uniform method used to reconstruct historical data series. As a result, the countries and areas included here are relatively wealthy and for the most part highly industrialized. The main goal of the Human Mortality Database is to document the longevity revolution of the modern era and to facilitate research into its causes and consequences. As much as possible, we have followed four guiding principles in creating this database: comparability, flexibility, accessibility, and reproducibility.