The contemporary legal systems of the world are generally based on one of four basic systems: civil law, common law, statutory law, religious law or combinations of these.
However, the legal system of each country is shaped by its unique history and so incorporates individual variations to the above. The science that studies law at the level of legal systems is called Comparative Law.
Both civil (also known as Roman) and common law systems can be considered the most widespread in the world: civil law because it is the most widespread by landmass, and common law because it is employed by the greatest number of people.
The central source of law that is recognised as authoritative is codifications in a constitution or statute passed by legislature, to amend a code. While the concept of codification dates back to the Code of Hammurabi in Babylon ca. 1790 BC, civil law systems derive from the Roman Empire and, more particularly, the Corpus Juris Civilis issued by the Emperor.
This was an extensive reform of the law in the Byzantine Empire, bringing it together into codified documents. Civil law was also partly influenced by religious laws such as Canon Law and Islamic Law.
Civil law today, in theory, is interpreted rather than developed or made by Judges. Only legislative enactments (rather than legal precedents, as in common law) are considered legally binding.
Scholars of comparative law and economists promoting the legal origins theory usually subdivide civil law into four distinct groups:
French civil law: in France and other former colonies
German civil law: in Germany, and past Germanic lands like Austria, Estonia, Bosnia etc.
Scandinavian civil law: in Denmark, Norway and Sweden
Chinese law: a mixture of civil law and socialist law
However, some of these legal systems are often and more correctly said to be of hybrid nature.