Final Answer:
A comedo is commonly called a blackhead.
Step-by-step explanation:
A comedo is a type of acne lesion characterized by a clogged hair follicle or pore. The term is often associated with two main types of comedones: open comedones, commonly referred to as blackheads, and closed comedones, known as whiteheads. A blackhead occurs when the hair follicle opening is wide, and the sebum (oil), dead skin cells, and bacteria within the pore are exposed to air.
The exposure to air oxidizes the contents, leading to a darkened appearance. The black color is not due to dirt but rather the result of the oxidation process. Comedones are a common feature of acne and can be managed through proper skincare and, in some cases, medical treatment.