A system of rules formulated and enforced by a particular society to regulate human behavior, with the objective of maintaining social order and promoting justice. The precise nature of law is a matter of long-standing debate.

Law encompasses a wide range of subjects. Common topics include the nature of law and legal reasoning, legal institutions and organizations (such as courts and government agencies), the history of law and legal systems, and the relationships between laws, people, and groups. The study of law also includes various subfields, such as international law, criminal law, constitutional law, family law, labor law, tax law, and business law.

The field of law has several characteristics that distinguish it from other sciences and disciplines. For example, statements about law are normative rather than descriptive or causal (as in the case of a law of gravity or a law of supply and demand). Additionally, laws are generally of a prescriptive nature (telling people what they must or may not do) rather than of a descriptive or predictive nature (as in the case of a scientific law such as the one governing gravity).

For these reasons, studying the laws and regulations of a country is often seen as a distinct discipline from the study of science or theology. Law is also unique in that it imposes constraints on the exercise of power, as discussed by Max Weber and others. These constraints reduce the asymmetry of political power and make it less arbitrary and coercive than would otherwise be the case.

While many philosophical theories of the nature of law are shaped by the specific legal systems and cultures in which they are developed, most legal philosophers have also found it fruitful to discuss the laws of a given civilization in a broader context. This allows them to view the laws in terms of their purpose and function, as well as their limitations and problems.

From a practical perspective, laws exist to help us accomplish the basic tasks of a nation: keeping the peace, maintaining the status quo, preserving individual rights, protecting minorities against majorities, and facilitating peaceful and ordered social change. Some laws do these things better than others, and the law is generally viewed as a source of pride and confidence in a nation.