Philosophy of law is a branch of philosophy that deals with philosophical questions about law. This chapter deals with one of these questions, which is perhaps the most fundamental one: what is the nature of law? philosophers of law have discussed this question for centuries, and apparently still disagree. This disagreement is partly caused by the fact that the question itself is ambiguous and can be asked with different purposes in mind. The chapter discusses the views of four legal philosophers, hart, dworkin, thomas aquinas and hobbes, to elucidate the different interpretations of the question what law is and the possible answers, including legal positivism and natural law theory. What the nature of law is