Law is the system of rules that a society or government develops to deal with crime, business agreements, and social relationships. The term is also used to refer to the set of laws that govern a particular geographic area, such as an entire country.

In most countries, the law is enforced by a government which citizens must follow or face punishment. There are many different laws that can be made, including those that prohibit murder, robbery, and other crimes. The law can also regulate business transactions and impose taxes. It can also create courts and determine what evidence is acceptable for a case.

The most common purpose of the law is to establish standards and maintain order, but it can also protect liberties and property. The law can be created by a group legislature, resulting in statutes; by the executive through decrees and regulations; or it may be established by judges through precedent, usually in common law jurisdictions. Private individuals may also create legally binding contracts or arbitration agreements that adopt alternative methods of dispute resolution to standard court litigation.

There are four universal principles that define the rule of law. These are that the law is clear, publicized, and stable; it is applied evenly; and the processes by which the law is adopted, administered, adjudicated, and enforced are accessible and fair.

Legal systems vary worldwide, and are based on various traditions. Some countries have civil law systems based on Roman law, with some influence from canon law and often supplemented or modified by local custom and culture. Other nations have common law, a combination of statutes and court decisions that is based on English jurisprudence and tradition.

Civil law systems are found on all continents and cover about 60% of the world’s population. They are characterized by the use of codes in small books that are easy for judges to read and understand, and by an emphasis on free contract and alienability of property. They differ from common law, a huge body of written case decisions that is difficult to understand and apply.

The main areas of law include criminal, civil, and administrative. Other specialties are property, corporate, and international law; family, maritime, and aviation law; and environmental law. In addition, there is a growing field of space law, which addresses international treaties and laws that apply to human activities in the Earth’s orbit and outer space. Other fields of law include discovery (the examination, before trial, by lawyers of facts and documents in the possession of their opponents) and en banc hearings. The latter are sessions of a court that have the full number of judges participating, rather than just a quorum. The decision of a judge or panel in such a session is known as a ruling.