Hair, general writing hair, is refers to the hair growth in the head, hair is not an organ, does not contain nerve, blood vessels, but contains cells, hair in addition to the increase in the aesthetic, mainly to protect the mind. Soft fluffy hair is elastic and can withstand lighter collisions and can help head sweat evaporation. The average person's hair is about 100,000 roots, in all hair, the length of hair is the longest, especially the woman with long hair. Some can grow to 90~100cm, even 150cm, but generally not exceed 200cm.
The color of the hair is determined by the genes, generally speaking, black, golden, brown and red, when the human aging, hair will usually become silvery. Hair in the world, because of race and region of different, there are black, golden, red brown, red brown, yellowish, gray, even green and red. Hair dye can also be dyed with a variety of colors. Scientific research proves that the color of hair is related to the difference of metallic elements contained in hair. Black hair contains equal amounts of copper, iron and melanin, and when the content of nickel increases, it will become gray and white. Golden Hair contains titanium, reddish-brown hair contains molybdenum, red-brown in addition to copper, iron, and cobalt, green hair is too much copper. In some countries in Africa, some children have a red hair, which is severely deficient in proteins.