What color is your hair? Is it long or short? Straight or curly? There are many factors that go into how your hair looks and feels, and even whether you’re likely to keep it as you get older.

The scoop on color and curl

A person’s hair color comes from a substance called melanin. The more melanin there is, the darker the hair. This same substance is responsible for skin color, so many times, people with darker skin have darker hair, and people with lighter skin have lighter hair.

Whether your hair is curly or straight, or thick or thin, depends on the follicles, which are groups of cells around the root of your hair. (The root is the spot that it grows out of, just like a tree or flower.) Some follicles grow straight hair, and some grow curly hair. Some grow thick hair, and some grow thin hair.

The really interesting part is that all of these can change. A baby can be born with dark brown hair, grow light blond hair and then grow up to be a teenager with medium brown hair. Someone with curls as a small child might be an adult with straight hair. And, of course, some older adults lose their hair, or their hair turns gray.

Dead, but growing!

It may seem creepy, but the cells that make up strands of your hair are actually dead. Hair grows because of the roots. The roots are alive, so they help the hair grow, but once you can see it on top of your head, on your arm, or somewhere else, the cells you can see are dead. That’s why getting a haircut doesn’t hurt, but getting your hair pulled can hurt your head.

Hair everywhere

Another important thing to understand is that you don’t just have hair on your head. Take a look at your arms and legs. Now take a close look at your face. You have hair everywhere on your body except for two places — the palms of your hands and the bottoms of your feet.

But don’t get too attached to your hair, because it won’t stay with you long. By the time you’re an adult, you won’t have any of the same hairs you have now. Each strand of hair will grow a few years, then rest for awhile, and then fall out. You can lose up to 100 hairs every day on your head alone! But don’t worry — new ones are always growing to replace the ones that fall out.