Girls generally begin to develop breasts at puberty, around age 10, with individual differences in timing. Breast development is the first feature of a girl’s secondary sexual characteristics. Some girls develop earlier, perhaps around the age of 8, while others develop later, around the age of 13. If a girl’s breasts develop too early or too late, it is recommended to visit a hospital to identify the causes and intervene. Girls’ breast development is affected by hormones and nutrition, so they should pay attention to nutrition and eat foods rich in protein and vitamins, such as eggs, milk, tomatoes and apples. It is recommended to choose loose and comfortable underwear and avoid wearing tight clothes or corsets, which may compress the breasts and affect the normal development. Physical exercise, adequate rest and relaxation, and avoiding late nights can be beneficial to breast development and body development. In addition, girls may experience slight itching, swelling and pain in their breasts during the development process, which is a normal phenomenon during the development period and need not be overly worried. If there are abnormal phenomena such as severe pain and palpable breast lumps during the development, you should seek medical examination and treatment.