Birds are warm-blooded, feathered vertebrates with beaks, wings, and a lightweight skeleton. They belong to the class Aves and are known for their ability to fly, although some species are flightless. Birds exhibit a wide range of sizes, colors, and behaviors, adapting to diverse environments worldwide. They lay eggs and have a unique respiratory system, with air sacs allowing for efficient oxygen exchange. Birds play crucial roles in ecosystems, contributing to pollination, seed dispersal, and insect control. Notable examples include eagles, sparrows, and hummingbirds, showcasing the vast diversity within the avian world.