A general distinction can be made between (a) civil law jurisdictions, in which a legislature or other central body codifies and consolidates their laws, and (b) common law systems, where judge-made precedent is accepted as binding law. Historically, religious laws played a significant role even in settling of secular matters, and is still used in some religious communities. Islamic Sharia law is the world's most widely used religious law, and is used as the primary legal system in some countries, such as Iran and Saudi Arabia.
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 organizations.
Numerous definitions of law have been put forward over the centuries. The Third New International Dictionary from Merriam-Webster defines law as: "Law is a binding custom or practice of a community; a rule or mode of conduct or action that is prescribed or formally recognized as binding by a supreme controlling authority or is made obligatory by a sanction (as an edict, decree, rescript, order, ordinance, statute, resolution, rule, judicial decision, or usage) made, recognized, or enforced by the controlling authority."
The Dictionary of the History of Ideas published by Scribner's in 1973 defined the concept of law accordingly as: "A legal system is the most explicit, institutionalized, and complex mode of regulating human conduct. At the same time, it plays only one part in the congeries of rules which influence behavior, for social and moral rules of a less institutionalized kind are also of great importance."