“Age of life” is one of the essential characteristics that differentiate people. Age perception is also associated with social justice. The concept of age is defined ambiguously. At the same time, the different age criteria also forms the basis of age differentiation and age discrimination. The population lead to distinctions of age groups, age categories, and generations. Differences between generations also lead to Study in the concepts of intergenerationality, intergenerational justice, and intergenerational policies.