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When you enter puberty, your brain starts to create sex hormones via a girls' ovaries or boys' testes. For girls, your body is producing extra estrogen and progesterone. Boys will receive more testosterone. Having extra hormones can cause changes to your body (like developing breasts for example) and also sometimes emotional changes. These are normal changes but can affect how you feel. Girls tend to start puberty around the age 8 to 13, whereas boys tend to start puberty a bit later from ages 9 to 14. Some children also enter puberty earlier or later than these ranges. If girls begin puberty before age 8 or boys before age 9, this is called "precocious puberty." If you notice your body changing early, speak with your parents or doctor immediately. Puberty does stop. Puberty is necessary for you to transform into an adult but you must be patient. Puberty can take as short as 1.5 years to as long as 5 years to finish. It is hard to know in the beginning how long it will last but it will eventually end! During the beginning of puberty, changing hormones cause breast development. Your hips will widen and you will gain pubic hair. You also should become taller. Two years after the onset of puberty, you might start having underarm hair and white or clear discharge on your underwear. Your period is likely to start soon. Around your period, you might experience premenstrual or menstrual cramps. Your abdominal region might hurt and you could feel bloated. It is totally okay if your breasts grow at different paces. They also might be sensitive to the touch at this time. You could gain anywhere from 2 to 8 inches in height. Some parts of your body, like your head and hands, could grow faster than your arms and legs. You might feel physically awkward during this period. Do not worry! The rest of your body will catch up! When your period starts, that means your uterus lining plus additional blood will leave your body once a month. Although menstrual cramps are normal, if the pain is unbearable, talk to your doctor. The sex organs will begin to develop. Your testes and penis will enlarge and you will gain pubic hair. Towards the middle of puberty, you will have a growth spurt. A few years after puberty has commenced, you will notice hair growth all over your body, including on your face. This will be a good time to learn how to shave and/or take care of your facial hair. Your body also will begin releasing testosterone. Erections and ejaculation commonly happen now. When you turn 14 or 15, puberty is almost to an end! Your larynx (e.g. Adam's apple) will be more pronounced. Your voice might crack and sound lower and deeper. One of your testicles might grow faster than the other one. This is normal! Boys can gain anywhere from 4 to 12 inches of height. You can continue growing until they are 18 to 20 years old. Testosterone is the sex hormone that causes your testicles to make sperm. You might become erect seemingly without cause. If you ejaculate in your sleep, that is okay. This is a "wet dream." As your voice changes, your pitch also could fluctuate wildly. This eventually will stop. Your brain will not be fully developed until you are about 23 to 25 years old. As your brain develops during puberty, it may be affected by risky behaviors, such as engaging in sex or trying drugs and alcohol. Be aware that any risky behaviors you engage in during puberty may lead to addictions later on.

Summary:
Realize what puberty is. Understand physical changes for girls during puberty. Understand physical changes for boys during puberty. Be aware that brain changes occur during puberty.