Final answer:
Dry skin is the result of sebaceous glands not producing enough sebum, which is vital for lubricating and protecting skin and hair.
Step-by-step explanation:
Skin that does not produce enough sebum is considered to be dry. The sebaceous glands within the dermis of the skin are responsible for producing sebum, which is vital for the lubrication and waterproofing of skin and hair. When these glands do not produce sufficient amounts of sebum, skin can become dry, lacking the natural lipids that provide its smooth texture and protective barrier. This can lead to various dermatological issues, such as irritation or an increase in sensitivity. It is important for these glands to function properly to maintain skin health, as sebum not only moisturizes but also has antibacterial properties and helps prevent excess water loss from the skin.