Law commonly refers to a system of rules created and enforced through social or governmental institutions to regulate behaviour, with its precise definition a matter of longstanding debate. It has been variously described as a science and the art of justice. State-enforced laws can be made by a group legislature or by a single legislator, resulting in statutes; by the executive through decrees and regulations; or established by judges through precedent, usually in common law jurisdictions. Private individuals may create legally binding contracts, including arbitration agreements that adopt alternative ways of resolving disputes to standard court litigation. The creation of laws themselves may be influenced by a constitution, written or tacit, and the rights encoded therein. The law shapes politics, economics, history and society in various ways and serves as a mediator of relations between people.

A legislature is a deliberative assembly with the authority to make laws for a political entity such as a country or city. Legislatures form important parts of most governments; in the separation of powers model, they are often contrasted with the executive and judicial branches of government.

Laws enacted by legislatures are usually known as primary legislation. In addition, legislatures may observe and steer governing actions, with authority to amend the budget involved.

The members of a legislature are called legislators. In a democracy, legislators are most commonly popularly elected, although indirect election and appointment by the executive are also used, particularly for bicameral legislatures featuring an upper chamber.