A sebaceous gland is a small gland in the skin which secretes sebum, a fatty substance that acts as a
protective and water repellant layer on skin and allows the epidermis to retain its suppleness; sebum also contains some antibacterial substances.
Sebum secretion is fairly constant but varies from individual to individual.
Obstructed sebaceous glands become blackheads which are the basis for acne.
Seborrhea is a disorder of the sebaceous glands characterized by over-production of sebum that results in red, scaly patches on the skin and dandruff. Common at puberty, it predisposes to dandruff.