The term law refers to a set of rules that are created and enforced by social or governmental institutions in order to govern conduct. Laws often are enforced by imposing penalties on people who break them.

Whether they are used to punish wrongdoers or to ensure that all citizens have the same opportunities, laws play an important role in our lives. They help to maintain peace and security, respect individual rights and ensure that governments, police officers and other public officials are held to the same standards as private citizens. They also serve to define and protect property rights.

Many countries have different legal systems. The United States, for example, uses a common law system, which means that its laws are based on judicial decisions (commonly known as caselaw) rather than legislative statutes. The law of stare decisis requires courts to follow earlier court decisions in the same jurisdiction when making new rulings on similar cases, thereby ensuring that similar issues are treated consistently.

Other countries use a civil law system, in which judges and barristers are bound by detailed legal codes when making their decisions. These codes are typically written by professional jurists and are intended to provide consistency in the application of the law.

In addition to its practical value, the law provides a fascinating subject for scholarly inquiry into topics such as legal history, philosophy and sociology. It also raises complex questions about the nature of justice, equality and fairness.