A body of rules that regulates a community and is enforced by a controlling authority, such as the police or a court. These laws are based on the customs and practices of the people, which may be partly derived from religious or spiritual texts, such as the Bible or the Koran. Law also refers to the discipline and profession that studies, applies, explains, and defends the principles of law.

Law encompasses a wide variety of fields and topics. A major part of it deals with the rights and duties that a person has under various situations. Examples include property law, which concerns ownership of land and all that is attached to it, including mortgages, leases and covenants. Personal property includes movable objects such as cars and jewellery, and it is protected by a kind of law called tort law which allows people to claim compensation when something damages their things. Other fields of law include intellectual property law, commercial law and trusts.

Another important field of law is criminal law, which involves punishment for crimes. This is mainly carried out by the police and courts, but it can be done through other means as well. The government tries to prevent crime through a system of laws, and it punishes those who break them by imposing fines or even imprisonment.

The Constitution of a country defines the basic structure of that government, and it lays out things like how the different branches of the government must work together. This is referred to as the separation of powers and ensures that one person cannot hold ultimate power and do what they want. The World Justice Project has defined the rule of law as four universal principles:

In addition to these general areas, there are many specialties in law which deal with specific types of agreements or relationships. For example, environmental law helps to protect the environment from pollution by imposing penalties on those who pollute. Aviation law is a particularly important field, and it deals with all the regulations that govern the use of aircraft, including their safety standards, which are set by the international body called the International Civil Aviation Organisation or ICAO.

A person who studies and applies the laws of a country is known as a lawyer, jurist or attorney. They can be either a transactional lawyer who makes contracts, or a litigator who goes to court. Both types are required to study and argue the law, but the latter can be more interested in interpreting the law rather than applying it to specific cases. They are also often more critical of recent changes to legislation, as is the case with this article.