Acne is caused when tiny holes in the skin, known as hair follicles, become blocked. Sebaceous glands are tiny glands found near the surface of your skin. The glands are attached to hair follicles, which are small holes in your skin that an individual hair grows out of.
There are three major factors that cause acne to develop: over-active sebaceous (or oil) glands, abnormal shedding of dead skin cells, and a proliferation of acne-causing bacteria. None of these factors have to do with skin care or lack thereof, and they all must be present for acne to occur