In Order to properly care for the hair, it is important to understand its structure. The two main parts that form hair are the root and stem. The root is hidden in the scalp, then widens, forming the bulb and finally transitions to the papilla, which nurtures the hair fiber. The stem (also called the shaft) is the visible part of the hair. The stem is composed of the cuticle (keratin flakes), the peel (hard protein) where the pigment is located that provides color to hair, and the marrow, the part that gives texture to the hair. Although the stem is formed of essentially dead cells, it still needs the care of shampoo, conditioners and repairing treatments to maintain its strength and flexibility.

·Elasticity: When hair is wet, it stretches significantly.

·Growth: Hair grows more prolifically than any other body cell. Heat stimulates hair growth, causing hair to grow faster in summer than in winter. Human hair grows approximately 5 inches per year. There are three steps in the growing process of each hair fiber and it has a limited life cycle. After the end of the hair life cycle (approximately six years), hair falls out.

·Quantity: People with red hair tend to have less hair, typically around 90,000, but the hair stems are generally thick. Blonds usually have more quantity, around 150,000, but the hair is normally thinner. People with brown and brunette hair color tend to be in the middle. Asians have more hair than any other ethnic group. Africans have a little less and Caucasians even less. Blonds tend to have oily hair due to the more dense follicle pattern which secrets sebum (fatty deposits). It is normal to lose approximately 50 to 100 hairs per day.

·Color: Hair color depends on the pigment color (melanin) found in each hair fiber. There are four basic colors: Red, yellow, brown and black. Human beings have a combination of these colors. Grey hair is really white hair, without melanin mixed with the original color.

·Type: If the hair follicle is vertically implanted into the scalp, hair will grow straight. If it is implanted tilted, hair will grow wavy or curly.

·Diet: Hair and nails, due to their fast growth rate, can indicate health changes. Hair growth starts in the hair papilla. Hair growth is a highly sensitive process and one of the areas affected first by illnesses. A well-balanced nutritious diet is very important for healthy hair. In many cases amino acid complements are beneficial in promoting healthy hair.

·Fashion: Hair deterioration can result from following fashion trends. All chemical treatments harm hair more or less; avoiding them is the best advice.

·Tightly pulled hair: When hair is pulled tightly on a daily basis the roots are weakened, which can result in hair loss in specific zones.

·Environmental factors: UV rays, wind, chlorinated or salt water and smog may cause hair fiber deterioration, allowing weakening and breaking of the hair. Dark hair can be especially sensitive since it absorbs more UV rays than fair hair. Hair needs extra protection when it exposed to these kinds of environmental factors.