Final answer:
Perming only the base of the hair adds volume and support, mostly beneficial for individuals with fine or limp hair, through the application of a chemical solution that changes hair structure at the base.
Step-by-step explanation:
Perming only the base of the hair is a technique primarily used to add volume and support to the hair. When the perm is concentrated on the base or roots, it effectively lifts the hair and creates a more voluminous look. This approach can be particularly useful for individuals with limp or fine hair seeking extra fullness. The process involves using either thermal or chemical means to alter the hair structure. For a chemical perm, specific chemicals are applied to the hair, and then it is wrapped around forms (such as rods) to produce the desired style. The hair closest to the scalp, or the base, is targeted to achieve this added lift and volume without necessarily curling the entire length of the hair.