Refers to the skin covering the top of the head. Used in medical, cosmetic, and everyday contexts.
My scalp is dry and itchy.
I massage my scalp every night after shampooing.
Scalp massage improves blood circulation.
In winter my scalp gets dry and itchy.
My scalp kept itching, so I went to the dermatologist.
Worried about thinning hair, I started scalp care.
頭 means the whole head as a body part, whereas 頭皮 refers only to the skin covering it.
Compound of 頭 (とう, 'head') and 皮 (ひ, 'skin'). A straightforward Sino-Japanese term.