Hormones are chemicals that help cells interact with each other. As already stated, both girls and boys have hormones; in girls, it's called estrogen; in boys, it's called testosterone. Estrogen causes a girl’s body to go through puberty.
Going through puberty, girls grow hair above and on the sides of their vagina.
Mood swings result from two things: one is the estrogen in your body. The other is the transition from childhood to womanhood.
Sometimes, pubescent girls want to do things they used to do before puberty but want to be treated like an adult. Also, at times girls want independence, but aren't mature and ready for full independence like an adult.
These factors might frustrate girls, and it is a good idea for a girl to talk with a grown-up she can trust about what she is experiencing.
