Our skin cells contain an oily substance called sebum which lubricates the cells and hair follicles.  Usually, sebum drains to the surface of the skin.  When sebum becomes blocked by a plug of oil and dead skin cells, trapped bacteria begins growing underneath.  The result is a whitehead.  Blackheads occur when an opening in the skin’s pores develops, exposing the melanin in sebum to air and causing it to turn dark.  Watch this video to to find out more of the differences between blackheads and whiteheads!