I refer blackheads and whiteheads to as comedones. On our face there is a lot of fine hair which are called villas hair, there is a gland attach next to this hair and the entire unit is called a pile of the sebaceous unit. Whenever there is a blockage of this hair follicle with either sebum or skin debris or keratin, this leads to the formation of comedones. If there is a thin layer of skin on top of the collection of the skin debris and sebum, then this leads to the formation of whiteheads. And when these comedones are exposed out in the environment, this leads to the oxidisation of keratin which leads to the appearance of blackheads.