Law is a set of rules that people follow to regulate their activities and provide security and stability. It governs many aspects of human life in societies that are governed by a central authority such as government. These include contract law, property law and criminal law. It can also control the use of goods and services by regulating their manufacture and distribution. Law can also be used to manage natural resources such as water and energy. It can also define and enforce social restrictions on behaviour such as censorship, crime and punishment. It can also control economic activity and protect human rights.

The word law comes from a Latin expression, legis, meaning “advice”. Its earliest definition was: “a rule imposed by those in authority upon those under them commanding what is right and forbidding what is wrong.” It is also defined as a general principle based on predictable consequences of actions or conditions: the law of supply and demand; or, more generally, a rule of natural or moral order: the laws of motion; the law of gravity; the laws of genetics; or, more broadly, a body of rules governing the construction of a work of art: the laws of grammar, playwriting or poetry.

Different countries have a variety of legal systems. The most common is the Common Law system found in the United States, which relies on the decisions of judges in court cases to decide what is law. Judges are sworn to make unbiased decisions based on the evidence presented in the case and must consider what would be fair and reasonable in a given situation. These decisions are then recorded in a legal dictionary called case law.

Another type of law is statutory, or legislative, which is enacted by parliament and is binding on everyone in the country. Other types of law are constitutional, administrative and regulatory. These are based on constitutional and public policy considerations, as well as the practical concerns of managing a complex society such as a nation-state.

The law also covers international matters such as immigration and nationality law, which deal with the rights of foreigners in a country and the problems of stateless persons. Other areas of the law include employment, insurance and commercial law. These areas of law are complex and constantly changing, as new social needs arise and existing laws must be interpreted and applied.

Lawyers are regulated by law in most jurisdictions to ensure they are ethical and professional. They must pass an examination to become a member of their local bar association and be admitted as a solicitor or barrister. In some countries lawyers have titles of honour such as Esquire to indicate a high level of practice or Doctor of Law to demonstrate their academic qualifications and commitment to the profession. They are also authorised to practise law under a statutory licence, which is typically overseen by an independent regulating body. This body may be a bar council or law society.