Dandruff (also called scurf and historically termed Pityriasis capitis)'s the excessive shedding of dead skin cells from the scalp. Dandruff can also be caused by frequent exposure to extreme heat and cold. As it's normal for skin cells to die and flake off, a small amount of flaking's normal and in fact quite common. Some people, however, either chronically or as a result of certain triggers, experience an unusually large amount of flaking, which can also be accompanied by redness and irritati… (More on Dandruff)