Law is a system of rules that a society or government develops in order to deal with crime, business agreements and social relationships. It can also refer to the profession of lawyers and judges, who work in this field.

A law can be a rule made by a government that citizens must obey or face punishment. It can also be a set of customs and practices that are binding in a community. For example, parents might have house rules they insist their children follow, which could be described as a law. Law can also refer to the way a person acts instinctively, such as when they try to save a life when in danger. This is often called the law of self-preservation.

People who argue about the nature of law tend to fall into one of three groups: utilitarians, natural lawyers and social Darwinists. Utilitarians argue that the main purpose of law is to satisfy social wants, such as the desire for security and property. They also point out that social change must happen gradually, and that laws are a means to achieve this.

Natural lawyers, on the other hand, argue that the main purpose of law is to preserve and protect human dignity. They believe that laws are morally right and that they are based on natural principles. Natural law developed concurrently with ancient Greek philosophy and was revived by philosophers such as Jean-Jacques Rousseau.

Legal systems vary around the world. The most advanced countries tend to use common law, while others have adopted a mixture of western and indigenous traditions. The legal system can also be affected by religion, culture and politics.

In addition to the major branches of law mentioned above, there are many sub-branches. Contract law regulates agreements to exchange goods, services or anything of value; criminal law deals with crimes committed by individuals and organizations; family law concerns marriage, divorce and child custody; tax law covers how much you pay in taxes; and constitutional law defines the fundamental rules of a state or country.

Other important law concepts include a complaint – a written statement by the plaintiff describing the wrongs they claim the defendant has done; a continuance – a decision by the judge to postpone the trial; and a counterclaim – the plaintiff’s response to the defendant’s claims. For more information about these and other aspects of the law, see statutory interpretation; legislative process; constitutional law; criminal procedure; administrative procedure; civil procedure; evidence law; and legal writing.