Horns are part of the body of some animals. They grow on the animal's head. They are projections (things that stick out) made of hard skin. The horn has a lot of keratin in it, the same protein that is in human hair and nails.
Normally horned animals will have two horns, but the rhinoceros has just one horn in the middle of its head.
Animals often use their horns for fighting one another.
- Antlers, structures similar to horns