A horn is a hard, pointed structure found on the heads of certain animals, such as cattle, goats, and rhinos. It is made of keratin, the same protein that forms human hair and nails. Horns can serve various purposes, including defense against predators, competition for mates, and social signaling among species. In addition to animal horns, the term "horn" can also refer to musical instruments, like the French horn or trumpet. These instruments produce sound by vibrating air within a tube, often made of metal. Horns in music are used in orchestras and bands to create rich, melodic sounds.