Law is a body of rules created and enforced to ensure that society functions smoothly. It is one of the most important subjects of study in a modern society and it provides a major source of scholarly inquiry into legal history, philosophy, economic analysis and sociology. It also raises important and complex issues concerning equality, fairness and justice.

The concept of law is so broad that it has spawned numerous specialties and subfields of study, each with its own methodology. The subject has so many facets that it may be best broken down into three categories, though they are not necessarily mutually exclusive:

A law is a rule or principle that governs some aspect of human activity. It may be normative in nature, prescribing how people ought to behave, or descriptive, describing the consequences of specific activities: the law of supply and demand is descriptive, but the law that criminals must be punished for their crimes is normative.

The laws of a country are a central component in the political structure that defines a nation, state or city. They set out the principles of how to deal with conflicts, and how to punish those who break them. They are often codified in statutes, which contain the specifics of how courts are to decide cases. They are usually supplemented by judicial interpretation, which is the basis of legal scholarship.

Some of the laws of a society are based on religious precepts: Jewish Halakha and Islamic Shari’ah are examples of this, as is Christian canon law. Law is also derived from scientific disciplines, such as physics and biology: the speed of light is a matter of physical fact, but how fast it goes is a matter of law.

From a methodological viewpoint, law is unique in that it is not subject to the same methods as empirical sciences (as the law of gravity) or social science (as the law of supply and demand). It is impossible to empirically verify whether a given law comprises certain precepts of such-and-such importance. It is also possible that a particular law may be more or less binding on different individuals depending on their predictions of how it intersects with an external reality that is shaped by the narratives of other people.

In the field of business, the law relates to everything from contracts that define exchanges of goods or services to regulations that determine how much tax to charge on a transaction. It is also concerned with property laws that define people’s rights and duties toward tangible possessions (like land or buildings) as well as intangible ones such as bank accounts and shares of stock. It also regulates labour relations and business practices, such as corporate governance. In addition, there is a growing area of space law that deals with the interactions between humans and outer space. There is even a branch of law that defines the rules of international treaties. Finally, there is an entire discipline of jurisprudence that concerns the logical development and interpretation of laws, including the practice of law.