Final answer:
Aging is a life-long process that starts after maturity. Adulthood is divided into stages such as early adulthood, middle adulthood, and old age.
Step-by-step explanation:
Aging is a life-long process that starts after maturity. Adulthood is generally the longest stage of life, potentially lasting for up to 80 years or longer. Although most physical growth and maturation are finished by the time adulthood starts, many changes occur during these decades of life. These changes make it necessary to divide adulthood into stages such as early adulthood, middle adulthood, and old age.