Along with facial features and eye color, one of the most prominent defining characteristics of a person is hair. Whether straight or curly, black, brown, blonde, or red, a person’s hair helps to set him or her apart from others.

If you look beyond the head, though, you’ll realize that the body is covered in hair. With the exception of the lips, the palms of the hands and the soles of the feet, there’s hair just about everywhere else on your body.

Regardless of where it’s growing, all hair comes out of the skin in the same way. Hair begins underneath the skin at a place called the hair root. This is where cells are grouped together to make keratin, the protein hair is made of. (Keratin is the protein that your fingernails and toenails are made of, too!)

Hair roots are the living parts of your hair, and they exist inside small tube-like places in the skin called follicles. As hair starts to grow, it rises up from the root and pushes out through the follicle.

Eventually it comes out of the skin where it can be seen. The part of your hair that can be seen above the skin is called the hair shaft.

Every follicle has tiny blood vessels at its base. These blood vessels feed the hair roots to keep them growing. By the time a hair has reached the surface of the skin, though, the cells within that piece of hair are no longer alive. That’s why it doesn’t hurt when you get your hair cut!

Hair follicles are also attached to sebaceous glands, often called oil glands because they produce oil that makes your hair shiny. If they make too much oil, your hair can look greasy. Don’t worry, though. A little shampoo takes care of that problem!

The average human has over 100,000 hairs on his or her head. And it’s a good thing! Would you believe that you lose about 50-100 hairs every day? It’s true!

You’ve probably seen them in the shower, the sink, the bathroom floor, and your clothes. Hairs fall out all the time, whether you’re washing your hair, combing or brushing your hair, or just sleeping peacefully.

Don’t worry! New hairs are always growing and replacing the ones that fall out. Each hair on your head goes through the same cycle.

Hair grows for somewhere between two to six years. The growth phase is called the anagen phase. Then it rests for a few months (called the telogen phase) and falls out. A new hair then begins to grow from the same follicle and the cycle repeats itself. At any particular time, about 85% of your hair is in the growing phase, while the other 15% are in the resting phase.

Most people’s hair grows at a rate of about a half-inch per month. That’s why most people get their hair cut every six to eight weeks when it grows longer than they like it. If you never cut your hair, would it keep growing forever?

Nope. Everyone has a maximum hair length, although most of us never know what that length is. Some people’s hair might never grow past their waist, while others might have hair that would grow to over five feet in length. Of course, it would take over 10 years for hair to grow that long, and most people would find hair that long to be quite uncomfortable and burdensome!

Wonder What's Next?

Can the air you breathe make things change colors? Find out tomorrow in Wonderopolis!