In this chapter, we're going to learn some animal facts about sheep. First off, sheep is a ruminant animal that lives on four legs. It's also one of the most numerous animals in the world. Sheep herding is a practice that's been used for thousands of years in most parts of the world, including the United States. Sheep skin is useful, too, because it's a good insulator against the chill of the wind. Sheep can also be used as a model animal in scientific experiments, since they were the first domesticated animals to be tamed.