what is dandruf? is it contagious? is it rash on the head or a fungus?

ANSWER TO THE ABOVE QUESTION Dandruff (Latin: Pityriasis simplex capillitii) is the shedding of dead skin cells from the scalp (not to be confused with a dry scalp). Dandruff is sometimes caused by frequent exposure to extreme heat and cold. As it is normal for skin cells to die and flake off, a small amount of flaking is normal and common; about 487,000 cells/cm2 get released normally after detergent treatment Some people, however, either chronically or as a result of certain triggers, experience an unusually large amount of flaking, up to 800,000 cells/cm2, which can also be accompanied by redness and irritation. Shampoos use a combination of ingredients to control dandruff. The pathogenesis of dandruff involves hyperproliferation of keratinocytes, resulting in deregulation of keratinization. The corneocytes clump together, manifesting as large flakes of skin. Essentially, keratolytic agents such as salicylic acid and sulphur loosen the attachments between the corneocytes and allow them to get swiped off.