Law is a system of rules established by sovereign authority that governs a country, state or group of people. It is used to control human behavior, punish criminals and settle disputes. Law is also an important part of the economy, regulating business and ensuring the safety of citizens.

There is a great deal of diversity in the legal systems of different nations. For example, the common law and civil law systems differ in their philosophies of law. The legal systems of many countries have a specific origin that can be traced through their judicial history. For examples, English law stems from the common law tradition and French law stems from the civil code. In addition, laws governing particular types of situations can be found under specific titles such as maritime law, labour law and property law.

A law is a set of rules created by a sovereign authority that forms the framework to ensure a peaceful society and enforces punishment if any rules are broken or breached. This is an incredibly broad definition, and it is often debated that law can be seen as the sum of all social norms, ethical codes and customs. Those who advocate that law is essentially a collection of social conventions and practices usually also argue that it should reflect the moral principles of a certain culture. These arguments are often referred to as natural law theories.

The most important functions of law are establishing standards, maintaining order, resolving disputes and protecting liberties and rights. For this reason, law is very complex and diverse, with many branches of law that regulate a wide variety of activities. For instance, contract law is a branch of law that regulates agreements to exchange goods or services, while property law encompasses rules regarding ownership and possession. This includes both real property (sometimes called real estate or land), which refers to the ownership of land and buildings, and personal property, which is all other movable objects such as books, clothing and vehicles or intangible objects, such as bank accounts and shares of stock.

Other branches of law include administrative law, which regulates the activities of government agencies and the procedures by which they operate; constitutional law, which is the body of laws forming the basic structure of a country; family law, which covers marriage and divorce; and criminal law, which deals with homicide, burglary and other crimes against person. Other areas of law that regulate the use of money include banking and financial regulations, which set minimum capital requirements for banks and best practice guidelines for investment; and water law, which governs how public utilities such as energy, gas, telecomms and water are managed and regulated. The responsibilities and privileges of lawyers are often described as legal practice or legal profession, and they are governed by a variety of rules, including a code of ethics and professional qualifications such as completing a law degree or course of study and passing a qualifying examination. Those who have achieved an official recognition of their legal status are referred to as being a lawyer, barrister or solicitor, and are often known by the honorific title Esquire or Doctor of Law.