If the hair is normal and healthy, each individual hair goes through a steady cycle of events: growth, fall and replacement. The rate of growth of human hair differs on specific parts of the body, between sexes, amongst races and with age. Scalp hair also differs among individuals in strength, elasticity and waviness. 
             The  growth of scalp hair occurs maor rapidly between the ages of 15 to 30, but declines sharply between 50 to 60. Scalp hair grows faster on women than men. Hair growth also is influenced by seasons of the year, nutrition, health and hormones.
             Climate conditions and seasonal changes affect hair in the following ways:
1) Humidity and moisture deepen the natural wave.
2) Cold air causes the hair to contract.
3) Heat causes the hair to swell or expand and absorb moisture.
             So, this is just a little info on "growth". Remember eating healthy, exercising and hormones play an important role in hair growth. 
             Take care of yourself so you'll have healthy hair.
 

Now DANDRUFF aka Dry Scalp consists of small white scales that usually appear on the scalp & hair. The medical term for dandruff is "PITYRIASIS". Long excessive dandruff can lead to baldness. Associated causes of dandruff are a sluggish condition of the scalp, possiably due to poor circulation, infection, injury, lack of nerve stimulation, improper diet and uncleanliness. 
There are two principal types of dandruff.: #1) PITYRIASIS CAPITIS SIMPLEX - that's your dry type. And #2) PITYRIASIS STEATOIDES- that's your greasy or waxy type.

Now heres how to fix it: Frequent Scalp Treatments, Mild Shampoos, Regular Scalp Massages, Daily Use of Antiseptic Scalp Lotions and Applications of Scalp Ointments. 
 
 

NOTE:  Both forms of dandruff are considered contagious and can spread by the common use of 
             brushes, combs and other home hair care articles (clips, rollers, etc.). So don't share.