Law is a system of rules established and enforced by social or governmental institutions to regulate behaviour and provide for the protection of individuals and communities against unjust and harmful practices. It can be regarded as either a science or art of justice, with its precise definition subject to ongoing debate. Law is a complex and varied subject, covering many different areas of life. It can be broken down into three broad categories for convenience, although some subjects may be seen as intersecting and overlapping:

The main purpose of law is to establish standards and to maintain order, resolve disputes and protect liberties and rights. In the absence of a clear, enforceable legal system people are left to their own devices, and this often results in chaos and inequality. The principle of the rule of law seeks to ensure that all people and institutions are accountable to laws that are publicly promulgated, equally enforced, and independently adjudicated. This also requires measures to ensure adherence to principles of supremacy, equality and fairness in the application of law, participation, separation of powers, legal certainty, avoidance of arbitrariness, and transparency.

In the modern world, law covers a wide range of subjects and has numerous sub-disciplines. Commonly referred to as ‘the legal system’, it is generally defined as the collection of rules, statutes and precedent that governs a state or nation. Law encompasses everything from contracts to property to human rights, and it is usually codified and interpreted by the courts.

Contract law concerns the rules governing agreements between parties. This includes everything from buying a car to trading options on the stock market. Property law defines a person’s rights and duties towards tangible items of value, such as land and buildings, and intangible assets such as stocks and shares. Labour law deals with the tripartite industrial relationship between employer, employee and trade union, and it involves collective bargaining, health and safety regulations and minimum wages. Criminal and civil procedure law involves the rules that must be followed by a court in a trial or appeals process. Evidence law refers to the materials that can be used in a court case.

Other types of law include religious, customary and international. Religious law is based on the teachings of a religion and includes Jewish Halakha, Islamic Sharia and Christian canon law. Customary law is a set of rules and traditions that are accepted by the community without being explicitly stated, such as etiquette or courtesy. International law is based on treaties and conventions that have been agreed upon by nations and bodies such as the United Nations.

Other aspects of law are more specific to individual countries, for example, immigration and nationality law relates to the right of citizens to live and work in another country, whilst water law is about the management of public utilities such as water supplies. In addition, tax law and financial regulation set out the rules that must be followed by companies operating within a jurisdiction.