Young adult (psychology)

# Overview
According to Erik Erikson's stages of human development, first enumerated in Childhood and Society (1950) a young adult is a person between the ages of 18 and 40, whereas an adolescent is a person between the ages of 12 and 17. The young adult stage in human development precedes middle adulthood. A person in the middle adulthood stage is between the ages of 40 and 65. In maturity, a person is 65 years old or older.

# Health
Young adults are generally in good health, subject to neither childhood disease nor the problems of senescence.
Biological function and physical performance reach their peak from 20-35 years of age, waning after 35. Strength peaks around 25 years of age, plateaus through 35 or 40 years of age, and then declines. Flexibility also decreases with age throughout adulthood. However, there are large individual differences and a fit 40-year-old may outcompete a sedentary 20-year-old. 
Women reach their peak fertility in their early 20s.  Assuming unprotected intercourse with a man of the same age, women aged 19-26 have about a 50% chance of becoming pregnant during a given menstrual cycle, compared with 40% in the 27-34 age group and below 30% for women 35-39. 
In developed countries, mortality rates for the 20-40 age group are typically very low. Men are more likely to die at this age than women, particularly in the 18-25 group: reasons include car accidents and suicide. Mortality statistics among men and women level off during the late twenties and thirties, due in part to good health and less risk-taking behavior. 
Cancer is much less common in young than in older adults. 
Exceptions are testicular cancer, cervical cancer, and Hodgkin's lymphoma. 
In sub-Saharan Africa, HIV/AIDS has hit the early adult population particularly hard. According to a United Nations report, AIDS has significantly increased mortality of between ages 20 to 55 for African males and 20 to 45 for African females, reducing the life expectancy in South Africa by 18 years and in Botswana by 34 years. 

# Early Adulthood
According  to Erikson, the young adult stage involves the personal need for intimacy and sex.  Failure to achieve this need results in isolation, which is avoided, and as a result the young adult strives for love and compassion. The young adult learns that love and compassion may get him what he wants.
In modern societies, young adults in their late teens and early 20s encounter a number of issues as they finish school and begin to hold full-time jobs and take on other responsibilities of adulthood. In the late teens and early 20s, young adults become individuals and will set themselves apart. Self becomes the main reliance. Young adults will strive to become independent from parents, take responsibility for themselves and make their own decisions. During the young adult stage, mainly the majority think in a more mature manner and take issues more seriously. They focus on the construction of a better future. Adolescents are generally regarded as naive and inexperienced, but are expected to grow into mature adults in their 20s. Young adults in this stage of human development learn value in both tangible and intangible objects. Their relationships with their parents and older adults change. However, in many cases, young adults and adolescents have enormous talent that can, in cases, outstrip some adults' talents. In many cases, problems such as lack of time (schooling and other commitments) and lack of money can arrest the adolescent's development in terms of intellectual and talent growth.

# Settling down
After the upheaval of the early 30's, the middle to late 30's (roughly ages 34-39) are often characterized by settling down. People in their 30's may increase the financial and emotional investments they make in their lives. Many have been employed long enough to gain promotions and raises. They often become more focused on advancing their careers and gaining stability in their personal lives. They may have started a family.