Let me explain:
A vertebrate is an animal with a backbone. There are many different types of vertebrates, including fish, amphibians, reptiles, birds, and mammals. Birds are a type of vertebrate that are characterized by their feathers. Feathers are a unique type of body covering that is made of keratin, the same protein that makes up human hair and fingernails. Feathers are lightweight and strong, and they help birds to fly. Birds also have beaks, wings, and a high metabolism.