Razor bumps are a type of ingrown hairs. There are essentially two ways hairs get trapped in your skin, creating bumps: transfollicular penetration and extrafollicular penetration. Transfollicular penetration occurs when the hair enters the skin without ever growing above the skin. It gets trapped before it has a chance to. With extrafollicular penetration (razor bumps), the hair has had a chance to grow above the skin, but it curls up and grows back into it.