A beak is a hard, pointed structure found in birds, used primarily for eating, grooming, and feeding their young. Unlike teeth, beaks come in various shapes and sizes, adapted to the bird's diet and habitat. For example, hummingbirds have long, slender beaks for sipping nectar, while eagles possess strong, hooked beaks for tearing flesh. Beaks are made of a protein called keratin, the same material found in human nails and hair. They play a crucial role in a bird's survival, helping them to forage for food, build nests, and communicate. The shape and size of a beak can also provide insights into a bird's evolutionary adaptations and ecological niche.