Law is the system of rules created by a society or state and enforced by that society to govern behavior. Its aim is to promote order, safety and security for its citizens. It provides a framework for dealing with disagreements and conflicts, as well as determining the rights and duties of individuals within a society. Law is also a source of profound philosophical debate and a significant field for scholarly research, including studies in legal history, philosophy, economic analysis and sociology.

The concept of law is complex because it incorporates both a normative and prescriptive element. It tells people how they ought to behave and what they can or cannot require from others, but also defines a set of rules that must apply equally to everyone. In this sense, law has a distinct character from empirical science (as the law of gravity) or even social science (such as the law of supply and demand).

Law shapes politics, economics, history and society in many ways. It is generally divided into two main categories, civil law and common law, although there are many other subdivisions such as criminal, corporate, labour and property. Civil law systems are found in the majority of countries, covering about 60% of the world’s population. These systems are based on concepts, categories and rules derived from Roman law and sometimes supplemented or modified by local custom or culture. Civil law systems have a more secular approach to legal issues than common law systems.

Common law systems are a small minority of the world’s population and are found in about 20% of the world’s countries. These systems have a more holistic approach to legal issues and place a greater emphasis on the equality of all persons. Common law systems have a system of precedent, whereby decisions made by courts bind other courts in similar cases. This is called the doctrine of stare decisis and helps to ensure consistency in court decisions.

Both systems contain a mix of civil laws, common laws and religious laws. Religious laws are generally based on the precepts of a particular religion, such as Jewish Halakha or Islamic Sharia, while Christian canon law still survives in some church communities. These religion-based laws are largely restricted to settling spiritual matters and are not generally enforceable in a civil context.

Law covers a broad range of topics, from commercial law to the study of how people think and behave (psychology of law). The core subjects are civil, criminal and administrative. Civil law deals with disputes between individuals, while criminal law involves behaviour that is harmful to a society as a whole and may result in a prison sentence. Administrative law concerns how government agencies and other institutions such as universities and hospitals are run, while evidence law decides what material can be used in a case. Many of these topics are intertwined and overlap, for example contract law relates to the exchange of goods and services and property law defines people’s rights and duties to tangible possessions such as houses, books or cars.