What is the cuticle of hair?

The cuticle of hair is defined as the outermost layer of the hair strand. It plays a critical role in protecting the inner layers of the hair, which include the cortex and medulla. The cuticle is composed of overlapping, scale-like cells that help to seal moisture in and prevent damage from environmental factors such as heat and styling products.

This protective layer is vital for maintaining the overall health and luster of hair. A healthy cuticle reflects light, giving hair a shiny appearance, whereas a damaged cuticle can lead to frizz and dullness. Understanding the function and structure of the cuticle is essential for cosmetologists when determining the best hair care products and treatments for different hair types.