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Puberty is when boys and girls bodies' start to grow into adult bodies and they start producing a chemical called a hormone.

Hormones cause changes in your body. You may notice things about yourself and your friends that start to change. Even though everyone goes through it, it can be quite a tough time, but learning about how your body will change can help stop some of your worries.

There's nothing you can do about it, our bodies will change when they are ready - everyone grows and changes at different rates. Don't panic if you develop at a different rate to your friends. There is no such thing as 'normal'.

Remember that there are lots of people who can answer your questions about puberty including your parents/guardian or a health care professional.

Some changes are the same for both boys and girls when going through puberty. These include:

• Your skin may become greasier and you may get outbreaks of spots
• Your body may sweat more and you may develop body odour
• Your body will grow taller – growth spurts are common
• Your sleeping pattern may change
• You may develop feelings towards people of the same and opposite sex
• You may feel emotional and have mood swings

Girls

Girls usually start puberty between the ages of eight and 14, but every girl is different. Some girls start puberty earlier and some later.

Girls' bodies start to develop the hormones Oestrogen and Progesterone that cause their bodies to change. It's normal for your body to experience the following:

• Your breasts start to grow
• Your hips will get wider
• You will grow public hair and hair in other areas of your body such as your underarm, and on your legs
• You will start to have periods

Periods are nothing to worry about – they are a normal part of every woman's life. Most girls start their periods from 10 to 16 years.

Periods are the start of a menstrual cycle. The menstrual cycle is the process during which an egg develops and is released from the ovaries. During each menstrual cycle the uterus grows a lining of tissue that prepares for a possible pregnancy. If the egg is not fertilised, the egg and the uterus lining will leave a girl's body through the vagina, which will cause bleeding that lasts for about three to eight days.

The average length of a menstrual cycle is 28 days however, some girls have longer or shorter cycles. Don't worry if it your periods aren't regular straight away - irregular periods can be normal. Some girls can get period pains during their period. If you are worried about your periods talk to your parents/guardian or a health care professional.

Boys

Boys usually start puberty between the ages of 13 or 14 years old, but every boy is different. Some boys start puberty earlier and some later.

Boys' bodies start to develop the hormone Testosterone that causes their bodies to change. It's normal for your body to experience the following:

• Your body may become more muscular and become broader
• You will grow pubic hair
• You will grow hair in areas of your body such as your underarms, legs, arms, face, chest and groin
• Your voice becomes deeper
• Your penis and testicles become bigger and your body will start to produce sperm
• You will start to get erections
• This is because your body is producing more sex hormones
• You may experience wet dreams where you ejaculate during your sleep

When a boy or man is sexually excited, his penis fills with blood making his penis stand away from his body and become harder. This is called an erection. You may experience unexpected erections - even though you may not be thinking about sex. Don't worry, this is normal.

For more information and listen to other young people talk about puberty, visit the NHS website ›