Dandruff is the shedding of flaky, white-to-yellow pieces of skin from the scalp. You may notice white dandruff flakes on your shoulders or collar area. Dandruff is the result of a common skin condition called seborrheic dermatitis, which may be seen in people with eczema, psoriasis, fungus infections, or overactive oil glands, among other conditions. Dandruff is not contagious, but it can be hard to treat. It is more likely to affect men than women. Follow the links below to find WebMD's comprehensive coverage about how dandruff develops, what it looks like, how to treat it, and much more.