Why do people clone plants and animals?

Human cloning is a topic of worldwide controversy and ethical and religious debate. It is already banned in many places. Some debaters argue in favor of human cloning for the purposes of initiating a pregnancy (reproductive cloning) and for medical research or treatment (therapeutic cloning). Debating these uses of cloning is complicated by the difficulty of reaching agreement about the definition of a human being (e.g., whether an embryo can yet be considered a human person). Further details on the pros and cons of human cloning are covered in other, similar questions on this topic in WikiAnswers.