Law is a set of rules decided by a place or authority meant to keep people safe and protect their rights. Law shapes politics, economics, history and society in many ways. The study of law involves understanding how it functions, how it is created, how it is interpreted and how it is changed over time.

A defining characteristic of laws is that they are enforceable by a centralized authority, which enforces them by applying penalties against those who do not obey them. This power is often exercised by a government, but may also be vested in other institutions, such as a business or a religious group.

There are a wide variety of different laws, which are categorized according to their subject matter or the type of activity they regulate. Examples include criminal law, which deals with punishing people for breaking the rules of a society; civil law, which deals with disputes between individuals; and property law, which defines their rights to ownership of land (called real estate), possessions and money (called personal property). Other areas of legal focus include intellectual property, which protects the right of people to their creations like music, art or literature; labor law, which governs the tripartite industrial relationship between employee, employer and trade union; tort law, which covers cases of negligence or injury; and constitutional law, which addresses important issues affecting the rights of citizens.

Interpreting law can be complicated, because judges and lawyers must decide how to apply the existing rules to a new situation. One way to do this is by examining the intended meaning of the original laws, which are typically written in fairly straightforward language. This interpretation is referred to as originalism. Another approach is to use principles and analogies, derived from previous rulings on similar cases. This is known as natural law.

A third way to interpret law is to consider the circumstances of a case in which it must be applied. For instance, a judge might determine that a statute must be interpreted in light of the purposes it was intended to achieve, as opposed to its literal wording. This approach is called contextualism.

The complexity of law is heightened by the fact that judges’ decisions are not always binding in other jurisdictions, and even within a jurisdiction, some courts have more authority than others. In addition, the practice of “stare decisis” means that judges must follow the rulings and decisions of higher courts when they are dealing with the same or a closely related issue. This is a way to avoid radical indeterminacy and bias. Just as linguists studying polysemy seek out the conditions of usage that determine its possible meanings, judges try to find the circumstances and conditions under which laws are appropriate, and then apply them. These are all attempts to ensure that the rule of law remains just, stable and clear.