What part of hair extends above the skin's surface?

The portion of hair that extends above the skin's surface is referred to as the hair shaft. The hair shaft is the visible part of the hair that we typically see, and it consists of layers of protein, primarily keratin. It is the part that is styled, dyed, and cared for in various ways in hairdressing.

In contrast, the hair follicle is the structure located beneath the skin that houses the root of the hair and plays a crucial role in hair growth. The hair bulb is at the base of the hair follicle and contains living cells that divide and grow, forming new hair. These components are essential for hair development and growth but are not visible above the surface of the skin itself.

Therefore, the correct identification of the hair shaft accurately reflects the part of the hair that is exposed and interactable on a day-to-day basis.