Permanent wave
A permanent wave otherwise known as a perm, are waves in the hair made by applying chemicals. The perm involves the use of chemical products to break and reform the bonds of the hair. 

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Types of permanent wave
There are two main kinds of permanent waves or perms. The first are spiral perms. A spiral perm uses permanent hair products with small curling rods, which produces tighter curls. Body waves however, make use of he same technique only with larger curlers that add a wavy effect instead of twisted ringlets.