Final answer:
Sebaceous glands, also known as oil glands, produce sebum to lubricate and protect the skin. Sebum waterproofs the hair and skin, preventing drying and inhibiting the growth of microorganisms on the skin.
Step-by-step explanation:
Another name for oil glands in the skin is sebaceous glands. Sebaceous glands are exocrine glands that produce a thick, fatty substance called sebum. Sebum is secreted into hair follicles and makes its way to the skin surface along with hairs. It waterproofs the hair and skin and helps prevent them from drying out. Sebum also has antibacterial properties, so it inhibits the growth of microorganisms on the skin.