The law is a system of rules that a society or government develops in order to deal with crime, business agreements, social relationships, property and finance. It is usually enforced by the state or a controlling authority through penalties, such as fines or imprisonment. Law also refers to the profession of advising people on the legality of actions and helping them defend their rights.

Many different definitions of law exist, with the precise nature of the term being a matter of considerable debate. It is widely regarded as a tool of social control, with laws typically reflecting the values and interests of the community they govern. Other theories of law focus on its role as a mediator of relations between individuals or between communities, as an instrument for achieving political goals, and as an institution that serves to satisfy societal wants or needs.

Laws can be created in several ways, such as by group legislatures, resulting in statutes; by the executive through decrees and regulations; or by judges through precedent, known as case law. Private individuals can also create legally binding contracts. Other fields of law include competition law, which deals with the regulation of businesses that seek to use their market power to stifle competition and raise prices for consumers; environmental law, which protects natural resources from pollution; and aviation law, which sets minimum standards for airplane safety.

There are also numerous subfields of law, such as criminal law, which deals with crimes such as murder and robbery, and civil law, which covers issues such as divorce proceedings and the rights of children. There is also international law, which deals with the right to asylum or the problem of stateless individuals; family law, covering issues such as marriage and divorce; transactional law, which involves business and money; and biolaw, which focuses on the intersection of law and the life sciences.

A career in law is increasingly attractive to young people, as the profession offers prestige and high salaries. Law can be a challenging and rewarding field, as the ability to think critically and logically is vital. In addition, lawyers have to be able to communicate well and work as part of a team.

The practice of law is overseen by either a state or an independent regulating body such as a bar association, bar council or law society. In order to practice, solicitors must pass a bar exam and have qualified by undergoing a legal education that normally leads to the award of an academic degree such as a Bachelor of Laws or a Juris Doctor. Some countries have specialised laws that require additional qualifications, such as a PhD in a relevant subject. Some jurisdictions have specific procedures that must be followed to register a foreign lawyer. These requirements can vary greatly between countries and may include a requirement to pass a legal practice examination. In some cases, professional registration can be denied if the lawyer is found to have breached ethical standards.