The types of hair are distinguished by its natural character, namely determined by the quantity of sebum the skin excreted. Of course, other facts also can affect the type of hair, such as marcel, dye, hot finalize the design, and so on.

Dry hairs are dry, lackluster, easy intertwist, and difficult to comb when become moisture after haisr treatment; the root of the hairs usually is thickness, but the tip of hairs normal is rarefaction, even with splits.
Oily hairs are thin, oily, always needs to be washed. Combination hair’s root same as oily hairs, but the tip like dry hairs.
Normal hair neither oily no dry; if without marcel or dye will always keeps its natural style. The hairs will be more cellularity, easy dryness and with more splits than normal hair, if it was marceled or dyed.

They are two reasons:
The first is without enough nutrition, for example with tummy bug or other diseases that can cause nutrition lack directly or indirectly.
The second include the tip splits cause by shampoos, other chemicals or physical element (such as hairs dry).

Hairs can reflect the condition of body. Hairs relate directly with body’s nutrition. 　
Amino acid vitamin A, B, C, D, E are necessary elements of hair grown, the microelement of copper, iron, Zn and others can prevent hair losing with pantothenic acid; the protein of gingeli, beans and the Ca of kelp and seashell with special function for hair smooth and light; fruits, meats, eggs, spinach, cabbage, celery, milk, black bean not only renew the cell, but also have some effect on prevent hair losing; chicken, fish, egg, beef, milk can push the protein’s compose of hair.
In a word healthy and abundant foods have consanguineous relationship with hair’s condition. Good shampoos and hair protecting products, properly frequency and way of washing can protect hair too.

A. There is a long time processes for hair's growth. When the soft horniness of hair cell become hard protein and was pushed out, it is hair.
B. More than 95% of man’s skin cover by hair, the average hair number is 100.000, the hair increase 1 cm. every month.
C. The normal diameter are 0.05－0.15mm, but Asian hair are thinner than occidental, so it give us an impress that black hair with more number than occidental.