The cuticle is the outside layer of a single strand of human hair, and it's the most resilient layer. The cuticle protects against damage to the more delicate inner layers of hair–the cortex and medulla–and also is the determining factor for how much shine and gloss your hair might have, depending on how well it absorbs light. There tend to be more cuticles on beard hair, which make it very coarse. Hydrating with warm water and shaving gel help soften the cuticles before taking a razor to it.