Perm is short for permanent wave. It is a hairdressing procedure which was used extensively in the past. Chemicals such as ammonia (referred to as a reagent) and/or heat are used to restructure hair. The same process can also be used to straighten hair.
WHAT TO EXPECT
A hairdresser will section hair, apply a reagent, and place small amounts of hair into curlers. Heat or tin foil may be used to increase the effect of the reagent. Hair is rinsed and curlers are unwound carefully. Hair is dried and styled. This can also be done from a home perm kit in the same manner.
Hair will have considerably more volume and can be styled in new ways. It dries hair which is a boon to greasy hair.
It is permanent, but the new hair growth will be of a different consistency. Hair can frizz and break due to the effects of the chemicals.