When something is artificial, or man-made, it has been made by humans, not nature. For example, an artificial satellite is one made by humans, while a natural satellite is a satellite that was not made by humans. Many artificial things imitate or copy things found in nature. The imitation may use the same basic materials as those in the natural object; or it may use quite different materials, as in Artificial leather. These are concepts in defining reality. There are different ideas about what can be considered artificial and what is natural.