What is the visible part of each strand of hair composed of multiple layers?

The visible part of each strand of hair is known as the hair shaft. The hair shaft is the portion of the hair that extends above the scalp and is made up of multiple layers, including the cuticle, cortex, and medulla.

The cuticle is the outermost layer, consisting of overlapping scale-like cells that protect the inner layers of the hair. Beneath the cuticle, the cortex provides the hair strand with strength, elasticity, and color due to the presence of melanin. The medulla, which may or may not be present in every hair type, is the innermost layer.

Understanding the structure of the hair shaft is crucial for haircolorists as it directly impacts how different hair products and coloring techniques will affect the hair. This knowledge helps professionals make informed decisions regarding the application of color and treatments to ensure healthy and vibrant results.