It refers to the increase in size, length and weight of all parts of the body, organs and tissues, as well as the soundness of their functions. Growth and development can be roughly divided into three stages: 1, infancy (under 3 years old – rapid growth period): birth to 3 years old, is the child’s rapid growth period. The first year of growth after birth is the fastest, with a growth rate of 25 cm. The second year growth rate is 10 cm. This period is mainly the regulation of nutritional status and growth hormone. 2.Childhood (3 years old – puberty, i.e. stable growth period): from the age of 3 until the beginning of puberty (about 10 years old for girls and 12 years old for boys), growth during this period is mainly regulated by growth hormone and thyroid hormone, with an annual growth of 5-7 cm. 3. Puberty (accelerated growth period): After entering puberty, children’s growth accelerates again due to the rise of sex hormone levels. Among them, growth hormone and sex hormone work together. In addition to promoting growth, sex hormone also promotes sexual maturation and epiphyseal closure, which eventually leads to the cessation of height growth. Throughout puberty, girls can gain 20-25 cm in height, while boys begin puberty 2 years later than girls, and therefore can gain 8-10 cm more height than girls.