Law is a collection of rules, whether written or unwritten, governing the way people act in society. These rules, or codes, shape politics, economics, history and society in many ways. Generally, they are created by people who have political power. Many countries have a constitution, which defines the overall framework of the law and sets out fundamental rights for citizens. Others have laws that are made by the legislature.

Usually, these laws are not written in very detailed terms because they are intended to apply to many situations. But they often have to be interpreted in individual cases, as judge after judge decides how the law applies to a specific set of circumstances. This process is called legal case analysis.

Some types of law are based on property, including land or real estate law and personal property laws. Other laws are based on contract law or commercial transactions, and still others, such as administrative or tort law, deal with disputes between individuals.

In common law legal systems, decisions by courts are considered part of the law, on equal footing with legislative statutes. This is known as the doctrine of stare decisis, or “to stand by decisions.” Judicial decision-making also incorporates a kind of cost-benefit analysis: judges consider how much an existing law would help in deciding a particular case, and weigh that against the difficulties involved in creating a new rule or regulation. In this way, the law continually evolves.