What is the name of the hard part of the nail?

The hard part of the nail is known as the nail plate. This component is a tough, protective layer that forms the visible portion of the nail. The nail plate consists primarily of a protein called keratin, which is also found in hair and skin, providing strength and durability. It extends from the nail matrix, and its primary function is to protect the sensitive structures underneath, such as the nail bed and the surrounding skin.

In contrast, the nail bed is the underlying skin beneath the nail plate, which supports the nail and provides it with nutrients. The bed epithelium is the layer of skin on the nail bed, while the hyponychium is the area between the free edge of the nail and the skin below it. Each of these structures has distinct roles in nail health and function, but they do not make up the hard protective layer that is primarily responsible for the nail's external appearance and protection.