Zit

There are different kinds. Whiteheads, or "closed comedones" are inside of a closed-off pore and the white comes from an antibody called leukocytes. Blackheads are also called "open comedones" and the dirt and oil in your open pores oxidizes and causes the dark color to form. Some whiteheads can be in a deeper layer of skin tissue and these are cystic. Some blackheads called "giant comedones" (the side of a dime or so) can actually be a type of skin cancer.