Individual development: The process of gradual change that occurs in stages, including quantitative and qualitative transformations. The term refers to the total life of an individual from birth to death, including progression as well as regression.

Phase-wise, that is, dividing this process into distinct stages, is a challenge in the field of childhood psychology. In his groundbreaking work The Problem of Age, L.S. Vygotsky examined individual development during childhood as a systematic process that progresses through stable and critical periods.

The development of the adult individual is a continuation of this process, with a program embedded in the evolutionary pattern of the species, after early adolescence, maturity continues to include stages such as: youth, adulthood, maturity, and all the way to old age.

It is important to note that the boundaries between these stages are not strictly defined, but rather depend on maturation patterns and regressions within the organism.

As multiple studies have shown, maturation and inversion processes are characterized by irregularity and temporal variation, this difference in processes, along with the asynchronous change in the individual’s states (temporal variation in the time of occurrence or development of processes), reflects internal contradictions in evolution, and offers diverse life possibilities, ranging from premature aging to longevity.