Children aged 7- 12.

13- 17 years old is a teenager.

18-45 years old is a youth.

46-69 years old is middle age.

& gt69 is old age.

According to developmental psychology:

0- 1 year in lactation, 0-2 years in infancy, and 2-3 years in infancy.

Preschool 3-6, 7 years old. 6, 7- 1 1, 12 years old preschool.

Adolescence is 1 1,12-14, 15 years old. Youth 14, 15-30 years old.

Middle-aged people aged 30-50. After 50 years old.

In the world, the population is usually divided into unequal groups according to the age of 0~ 14, 15~64 and over 65 years old, which are called juvenile population, mature population and elderly population respectively.

The juvenile population coefficient, the mature population coefficient and the elderly population coefficient are calculated according to the total population, and the dependency coefficient is also calculated according to the mature population.

That is, dependency coefficient = (juvenile population+elderly population)/mature population 15~24 years old population is also called young population internationally.

Extended data

Division of Traditional Age Groups in China

Childhood: 1 _ _ 7 years old;

Juvenile: 8___ 16 years old;

Youth: 17__29 years old;

Standing: 30 years old; (Old name: thirty years old)

Yishun: 40 years old; (formerly known as the year of listening)

Know your destiny: 50 years old; (Old name: 50 knowing the destiny)

Flower armor: 60 years old; (Old name: Sixty Flowers)

Gu Xi: 70 years old; (Old name: 70 years old)

Octogenarians: 80__99 years old; (Old name: octogenarian)

Life span: 100 years or older.

Baidu Encyclopedia-New Era Subdivision