Law is the set of rules made by a society or government which it uses to regulate behavior and contract relationships. These laws are enforced by a controlling authority through penalties (such as fines, jail time or loss of job). Law serves many purposes: establishing standards, maintaining order, resolving disputes and protecting liberties and rights. The term is also used to refer to the profession of a lawyer or judge, as well as the study of systems of laws and how they work.

The term law is also sometimes used more broadly to refer to all the laws of a specific geographic area, country or community. This type of law would include laws about things such as traffic violations or murder, and it might include other kinds of restrictions, such as bans on smoking in certain places or a requirement that all children be immunized against diseases.

Different countries have different legal traditions. For example, the U.S. employs a common law system, in which judges make up the rules of the land by evaluating previous court decisions on similar cases. Other countries, such as Japan, have civil law systems, in which judicial authority follows a codified set of statutes. Civil law is regularly updated, with the goal of reducing bias in the judging process.

Some of the most important areas of law include employment, family and environmental protection. Employment law covers the tripartite relationship between worker, employer and trade union, including the right to strike. Family law encompasses laws about marriage, divorce and adoption, as well as child custody and parental rights. Environmental protection is a key part of many national legal systems, with laws designed to protect air and water quality, and to penalise polluters.

There are also a wide range of specialized areas of law, such as banking and finance, aviation, and intellectual property. Banking and finance laws are designed to ensure financial stability, through such measures as deposit and withdrawal limits. Aviation law is a very important field, with laws governing the safety of aircraft and the conduct of pilots. Intellectual property laws protect the ownership of inventions and designs, and are an important part of economic development in some countries.

The study of law is multi-disciplinary, involving many different academic disciplines. The fields of sociology and social work, for example, are concerned with how the law is applied in practice, and what influence the underlying social and political structures have on the development of laws. The study of law is therefore an extremely important and interesting one, which has influenced many aspects of human existence. It is no wonder, then, that careers in the field are so popular. Law is a fascinating subject, and one which can provide many exciting and rewarding opportunities. For more information about this field, see the articles on legal profession, legal education and legal ethics. See also Constitution; ideology; and political system.