The laws of a country set out rules on what people can and cannot do, and the way in which these are enforced. The study of law is often divided into two broad categories: the study of the legal system itself (law) and the study of how it shapes society (legal studies). The most important areas of the law are criminal and civil, the former dealing with issues involving the criminal justice system and the latter providing an avenue to help resolve noncriminal issues between parties through the court system. Law is also used at the international level to establish rules on such matters as trade, the environment or military action.

The earliest laws were probably written by leaders to set out basic rules about how people should live together and interact with each other. Today most countries have a constitution which sets out the overall framework of the society and additional laws, called statutes, deal with details. In most democracies the people choose politicians to represent them in a legislature, such as Parliament in London, Congress in Washington or the Duma in Moscow. Legislators write laws and vote on whether to pass them. The courts interpret the laws and decide on what they mean in specific cases. The decisions of one court are binding on other courts in the same jurisdiction, but those of higher courts have more influence than those of lower courts.

Most societies have a wide range of laws to cover the most common situations that arise in everyday life. Contract law regulates agreements to exchange goods and services, such as buying a bus ticket or trading shares on a stock market. Property law defines people’s rights and duties toward tangible possessions, such as land or buildings, and intangible assets, such as bank accounts and shares of stock. The law of torts covers the way in which people can be compensated for injury and damage caused by others.

A lot of debate takes place about what is actually ‘the law’, and this is a central area of study for students of law. A lively debate for example is over whether judges should be allowed to follow their own inclinations in the interpretation of the law, rather than being bound by a ‘code’ or ‘rules’ that have been laid down before them. This kind of discussion is a key part of the law’s ongoing evolution and makes it an interesting area to explore.