Law is a set of rules that governs relationships between people. It shapes politics, economics, history and society in various ways. For example, laws regulate how businesses operate and the activities of government agencies. Law can also shape the rights of individuals, and the relationship between states and their citizens. Law can be a source of conflicting pulls as different interests compete for recognition. See the articles on the legal profession, legal education and legal ethics for more information. The law may be created by legislative authority or through custom and practice. It can be influenced by political philosophy and social values, and is often coercive.

The legal system varies around the world, with some countries having only one legal tradition. However, there are certain basic principles common to most legal systems. These include the separation of powers, a hierarchy of courts and the importance of legal precedent.

Most legal systems have a criminal and civil law, with the former covering crimes against the state and the latter disputes between individual citizens. Laws governing contracts and property are examples of civil law, while censorship, punishment for crime and the military are examples of criminal law. Some legal systems, like that of the United States, have both federal and state jurisdictions over their citizens. The laws of the states are mainly based on the constitution, but many of these are supplemented by statutes and administrative regulations.

Laws can have a wide variety of purposes, but most are designed to ensure that the peace and welfare of the citizenry are protected. The rules are usually set by a legislature, such as parliament in the UK, but are sometimes determined by a supreme court. Judges in the United States are guided by a doctrine called stare decisis, which means that decisions of a higher court should be followed by lower courts.

Different theories of law try to determine the purpose of legislation and rules. The utilitarian view, advocated by Jeremy Bentham and John Austin, is that the law should serve the interests of society. Jean Jacques Rousseau promoted the idea of natural law, which is that there are unchanging laws of nature. Some people, such as William Wilberforce and John Locke, have argued that these natural laws are inviolable and that a government should be limited to enforcing them.

Hans Kelsen’s pure theory of law is that it is a normative science that creates the standard by which actions are judged. Law, according to Kelsen, reflects the common consciousness of a society and is superior to statute.

Law is a vast area of study, and the articles below provide some introductions to the main topics. The articles on constitutional law, family law and corporate law are particularly recommended. The law also affects the environment, and this is a topic discussed in environmental law and climate change. The law can also be applied to specific groups, such as minors, the elderly or people with disabilities, and this is the subject of child law and disability law.