The aging process has been studied at the molecular and physiologic level for decades, and many theories have been proposed for why this universal phenomenon evolved. Multiple tissue-level changes occur with aging, including chronic, “sterile” inflammation; cellular senescence; macromolecular damage, and progenitor cell function decline. These changes underlie age-related pathologies that lead to a decline in global function of the individual. In the study of aging biology, there is much to be learned from exceptionally long-lived humans, such as centenarians, as well as animal models of exceptional longevity, like the naked mole rat. In addition, attention should be paid to disparities that exist in life span even within the United States. Importantly, drugs have been developed that extend life span, enhance health span, or delay or alleviate age-related conditions in mice. The field of aging biology is more poised than ever to turn toward the translation of basic research findings into clinical applications that might extend human health and life span.