The transition from adolescence to young adulthood is a long process, which - like puberty - proceeds in chronologically and culturally different ways in each individual. For these transition phases, a period between the ages of 18 and 25 is estimated, during which various developmental milestones should be overcome: increasing financial and legal independence and self-responsibility, transitioning from group to individual orientation, starting more stable personal relationships, coming to terms with self-image and the obligations of adulthood, increasing the transfer of responsibility for others, and leaving the family unit. From a medical point of view, independence, self-responsibility, and decision-making are significant factors of a paradigm shift ( e.g. a medical treatment contract). Although this paradigm shift is fixed to an appointed day legally ( e.g., the 18th birthday), in postmodern industrial societies this correlates neither with self-image nor with the real process of progress.