Final answer:
Sebaceous glands produce sebum, a thick, fatty substance. The secretion of sebum helps waterproof the hair and skin, prevents drying out, and inhibits the growth of microorganisms on the skin.
Step-by-step explanation:
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. Sebaceous glands are found in every part of the skin except for the palms of the hands and soles of the feet where hair does not grow.