Law is a system of rules created through social or governmental institutions to regulate behaviour. It is enforced by mechanisms which punish those who break the rules. It shapes politics, economics, history and society in many ways and acts as a mediator between people. Law can be categorized as civil, criminal or administrative.

Civil law includes fields such as property, contract and family law. It differs from common law, which derives its laws from judicial decisions on specific cases that have been brought to trial. Civil law systems often rely on codifications (either by legislature, resulting in statutes, or by executive decree, resulting in regulations) and case law.

Criminal law covers offences against the state and aims to deter others from committing crimes. It encompasses criminal procedure, which sets out how courts should operate, as well as evidence and trial procedures. The law of war and the treatment of prisoners are also covered by criminal law.

Administrative law concerns the management of public services such as water, electricity and gas. It deals with regulating businesses that provide these services and also how they are governed by the law.

It is a multi-disciplinary field and encompasses many different areas of study, including philosophy, sociology, anthropology and cultural studies. Some of the most important developments in the history of law have come from philosophers, such as Locke, and behavioural economists such as von Mises. Law is a complex and diverse subject and its relevance extends into all areas of life.