The scalp has two main layers of skin. The inner layers are called the dermis, which contain oil and sweat glands, blood vessels, cells, tissues, and hair follicles. The outside layers are called the epidermis, which contain the mouths of the hair follicles and protect the sensitive dermis layers. The dermis layers secrete many important substances to the epidermis layers, such as oil and sebum, that are needed to keep the scalp lubricated and pH balanced. Knowing and understanding the layers of your scalp are necessary parts of a healthy hair lifestyle.