Humans live longer today than ever before. The remarkable rise in longevity occurred in a brief period of human history, roughly since the eighteenth century, and was driven by persistent efforts against epidemics, famines, health insecurity and chronic diseases. This chapter covers essential concepts regarding this extraordinary achievement for the human race, such as the demographic transition model, distinguishable from the earlier Neolithic demographic transition, which both led in their unique way to substantial alterations in the cause and age distribution of deaths. To account for the shift in disease patterns over time, the concept of epidemiological transition was originally proposed by Abdel Omran in the early 1970s and later evolved into broader conceptual frameworks, including the health transition. The chapter concludes by briefly addressing whether increased human longevity is matched by improved health and its future sustainability.