Sebaceous glands are small glands present throughout the skin in human body (except soles and palms) and generally exist near the hair follicles. These glands secrete an oily substance known as sebum, which is a mixture of lipids and wax. The main functions performed by sebum are :
1) Protect the skin from drying and cracking by lubrication and waterproofing.
2) Anti-microbial action: Prevent the growth of microorganisms on skin.
3) Keep the hair follicles free from dust, germs and skin debris.