Hard keratins are a type of fibrous protein found in certain structures of the body, such as hair, nails, and the outer layer of skin. They are characterized by their toughness and resistance to wear and tear, making them essential for protecting underlying tissues. Hard keratins are composed of tightly packed protein chains that form a strong, durable structure. These proteins differ from soft keratins, which are more flexible and found in other tissues. Hard keratins play a crucial role in providing mechanical strength and protection, helping to prevent damage from environmental factors and physical stress.