Haircuts don’t hurt because your hair is not alive. Hair is made out of a protein called keratin. Only the root of the hair—the part that grows inside the skin on your head from tiny holes called follicles—is alive and growing. So if you pluck out a hair by the roots, it hurts. But trimming or cutting your hair is painless. And that is also the same reason why it doesn’t hurt to trim your fingernails or toenails, which are also made of keratin. And because fingernails grow faster than toenails, you need to trim them more often!