In one sentence, describe what the following article is about:

Dandruff, clinically referred to as seborrheic dermatitis, often presents in a yellowish-whitish color. Therefore, try examining the patches on your head. If it's more silvery white, it's likely psoriasis. If it's more yellowish, it's more likely dandruff. Psoriasis often presents as fairly powdery or dry, so check the patches on your head for greasiness. If it seems greasy, it's more likely dandruff than psoriasis. You may even be able to tell just from looking at it whether it seems greasy or dry. Dandruff usually stays just on the scalp rather than moving past the hairline. Therefore, if you notice patches that move past the hairline, that's more likely to be psoriasis than dandruff. If it stays just on your head, it could still be either psoriasis or dandruff. . Ringworm may be mistaken for psoriasis or dandruff as well. Ringworm causes bald patches on your head that are itchy and scaly, which may seem like a dandruff problem or psoriasis. However, ringworm is a fungal infection, which requires treatment with antifungal medications. See your doctor to be sure about what is causing the flaking on your head.

Summary:
Look for a yellowish color for dandruff. See if it's greasy or dry. Notice where your patches end. Check to see if it might be ringworm