Law is the system of rules created and enforced by social or governmental institutions to regulate behavior. It has many purposes, but four are often mentioned: establishing standards, maintaining order, resolving disputes, and protecting liberties and rights.

The precise nature of law is the subject of intense philosophical debate. Some theorists claim that it has a natural, unchanging essence that can be uncovered through careful analysis. Others maintain that laws are merely human constructs that depend on the particular cultures in which they are created to make sense.

A significant source of interest in the study of law is its role as a mediator between people. Law can shape politics, economics and history, as well as govern the distribution of power in society. This function is especially important in societies that are divided into multiple jurisdictions, where a central authority cannot directly control all aspects of life.

Other sources of interest are the normative aspects of law, such as its purported ability to give rise to reasons for action. In the past, philosophers have debated whether or not there are any features that are essential to law, and if there are, what these might be.

Attempts to answer these questions have produced a wide variety of theories of law. Some of them try to systematize the data that are relevant to the concept of law (or cognate concepts, like legal validity or legal obligation). Other theories of law seek to explain why we find the idea of a law attractive or appealing, in which case they attempt to capture some of our intuitions about what makes certain laws “right” or “wrong”.

Another controversy concerns the extent to which law relies on coercion. Some theorists, such as Hans Kelsen, argue that law’s ability to impose sanctions is crucial for its social functions. Others, such as Joseph Raz and H.L.A. Hart, deny that coercion is a necessary feature of law, and assert that the content of law is entirely contingent on human choices and mental operations.

Despite the debate on the nature of law, there is no doubt that it shapes all aspects of human life in various ways. Every person in a democratic country lives under the influence of law, and most people are affected by a variety of legal fields. Contract law regulates the exchange of goods or services, while property law defines people’s rights and duties to tangible property, and tort law compensates victims for harms caused by others, such as in a car accident or defamation. Criminal law, on the other hand, deals with offenses against the state, such as robbery or murder. These and other areas of law are regulated by different systems of legal knowledge. In most of the world, law is based on legislative systems, in which a central legislature codifies and consolidates its laws, or on common law systems, where judges create law through interpreting precedents. However, some regions continue to follow religious law traditions, such as Jewish Halakha or Islamic Sharia.