⟩ In what year of life are more than 50% of people born in a particular year dead.
Many factors go into actuarial calculations. Among them are gender, socio-economic factors, nationality, race, and even "years of peace" in a given region. So if you looked at a place like Somalia, life expectancy is very low, 35 or 40. This means that there is very high infancy mortality and that most die by the time they are in their mid to late 20's. This is due in part to warfare, hunger, drought etc... On the other hand, the US has a much higher life expectancy rate and a relatively low infancy mortality rate.
