Keratins are a type of protein that play a crucial role in the structure of our skin, hair, and nails. They are tough and fibrous, providing strength and protection. In humans, keratins help form the outer layer of the skin, making it resilient against damage and dehydration. These proteins are also found in animals, contributing to the structure of feathers, hooves, and horns. Different types of keratins exist, with some being more flexible, like those in hair, while others are more rigid, like those in nails. Overall, keratins are essential for maintaining the integrity of various tissues in both humans and animals.