Law is a system of rules and customs developed by a society to deal with crime, trade, social relations, property, finance and more. Its unique characteristics make it a subject of scholarly inquiry in areas such as legal history, philosophy and economic analysis, and it raises important and complex issues concerning equality and fairness. It is therefore not easy to give a definition of Law, and many books containing numerous different ideas and definitions have been written.

The main purpose of Law is to ensure the safety and welfare of citizens, protect the property rights of individuals, promote equality and justice and facilitate social change. However, some laws are more effective than others in fulfilling these purposes. For example, a government ruled by an authoritarian leader may keep the peace and maintain the status quo, but it will also oppress minorities and suppress political opponents. In contrast, a democratic government will generally promote social justice and allow for peaceful social change.

There are three main categories of Law: criminal, civil and administrative. Criminal law deals with offences against the state and the punishment of those who commit them. Civil law deals with disputes between private parties and provides compensation when someone has suffered a loss or injury, for example through an automobile accident or defamation of character. Administrative law deals with the rules that govern the operation of public services and utilities, such as water, energy and telecommunications. These are usually covered by legislation but can also be established through a judicial decision or by an executive order.

The concept of Law has been defined in many different ways by scholars and jurists. Most modern legal theorists agree that it is an instrument for promoting social justice and protecting individual rights. This is achieved by ensuring that the needs of a community are met and that those rights are clearly expressed, with remedies for breaches of those rights. It is also an instrument for adjusting to changes in the community by using creative jurisprudence, such as interpreting existing rules to meet new requirements.

Other theories of Law are less analytical, such as those of Savigny and the sociological school, which began in the nineteenth century. The latter focuses on the effect of law on society and views it as an outcome of social habitat and experience.

The concept of Law is complex from a methodological point of view, because it contains normative statements that are deprived of the descriptive or causal character of statements in empirical science (such as gravity) and even social sciences. This makes it difficult to compare and contrast with other subjects, and a lot of work has been done by scholars to try to find a definition of Law that is both accurate and comprehensive. A number of different methodologies have been used, including: the naturalistic approach of John Austin, the logical positivism of Hans Kelsan and the sociological approach of the neo-realist school. All these approaches have their advantages and disadvantages.