Law is a term which does not have a universally accepted definition, but one definition is that law is a system of rules and guidelines which are enforced through social institutions to govern behaviour. Laws can be made by legislatures through legislation (resulting in statutes), the executive through decrees and regulations, or judges through binding precedents (normally in common law jurisdictions). Private individuals can create legally binding contracts, including (in some jurisdictions) arbitration agreements that exclude the normal court process. The formation of laws themselves may be influenced by a constitution (written or unwritten) and the rights encoded therein. The law shapes politics, economics, and society in various ways and serves as a social mediator of relations between people.

A general distinction can be made between civil law jurisdictions (including canon and socialist law), in which the legislature or other central body codifies and consolidates their laws, and common law systems, where judge-made binding precedents are accepted. Historically, religious laws played a significant role even in settling of secular matters, which is still the case in some countries, particularly Islamic, and some religious communities, particularly Jewish Halakha. Sharia law is the world's most widely used religious law.

The adjudication of the law is generally divided into two main areas. Criminal law deals with conduct that is considered harmful to social order and in which the guilty party may be imprisoned or fined. Civil law (not to be confused with civil law jurisdictions above) deals with the resolution of lawsuits (disputes) between individuals or organisations. These resolutions seek to provide a legal remedy (often monetary damages) to the winning litigant.

Under civil law, the following specialties, among others, exist: Contract law regulates everything from buying a bus ticket to trading on derivatives markets. Property law regulates the transfer and title of personal property and real property. Trust law applies to assets held for investment and financial security. Tort law allows claims for compensation if a person's property is harmed. Constitutional law provides a framework for the creation of law, the protection of human rights and the election of political representatives. Administrative law is used to review the decisions of government agencies. International law governs affairs between sovereign states in activities ranging from trade to military action.

To implement and enforce the law and provide services to the public by public servants, a government's bureaucracy, the military and police are vital. While all these organs of the state are creatures created and bound by law, an independent legal profession and a vibrant civil society inform and support their progress.

Law provides a rich source of scholarly inquiry into legal history, philosophy, economic analysis and sociology. Law also raises important and complex issues concerning equality, fairness, and justice. There is an old saying that 'all are equal before the law.'. The author Anatole France said in 1894, "In its majestic equality, the law forbids rich and poor alike to sleep under bridges, beg in the streets, and steal loaves of bread." Writing in 350 BC, the Greek philosopher Aristotle declared, "The rule of law is better than the rule of any individual." Mikhail Bakunin said: "All law has for its object to confirm and exalt into a system the exploitation of the workers by a ruling class". Cicero said "more law, less justice". Marxist doctrine asserts that law will not be required once the state has withered away.