Law is a system of rules created and enforced by social or governmental institutions to regulate behavior. Its precise definition is a matter of longstanding debate and it has been variously described as both a science and the art of justice. It serves many purposes, but the principal ones are establishing standards, maintaining order, resolving disputes and protecting liberties and rights. Laws may be made by a collective legislature, resulting in statutes, or by the executive branch, in the form of decrees and regulations. Individuals may also create legally binding contracts. Law is not easily compared with other sciences or disciplines as it is normative, that is, it dictates how people ought to behave or what they are permitted to do. It cannot, however, mandate behaviours that are impossible given the shape of the physical world and human capacity.

A legal system is based on a mixture of statutes, regulations and case law, with differing amounts of each depending on the country in question. Some countries, such as the United States, employ a common law system in which decisions by judges are considered law on equal footing with statutes and executive decrees. This is known as the doctrine of precedent or stare decisis. Other countries, including Japan, operate under a civil law system in which legislative statutes are more detailed and judicial decisions are not binding on other courts (although they can influence future case law).

In any legal system it is important to be aware of the terms used and what their meanings are. Some of the most commonly used terms include:

Appeals – The act of requesting another court to review a decision of a lower court or tribunal. An appeal can be made by either the plaintiff or defendant. The party who files an appeal is called the appellant.

Evidence – The material presented during a trial, such as witness testimony or documents. Generally, evidence is considered to be admissible when it has been obtained legally and properly. Inadmissible evidence is that which is unreliable, biased or prejudicial and should not be admitted in court.

Jury – A group of people selected to hear and decide upon the facts of a dispute during a trial. A judge will typically give instructions to the jury regarding the law and what they should consider when weighing evidence.

Sequester – The process by which a jury is removed from the public eye during a trial, normally to protect them from outside influences that could impact their deliberations. A jury is often sequestered during a capital offense trial or a case with sensitive information such as a child molestation.

The law is an important part of society and a key element in any government. It helps to ensure that the needs of all are met and provides a framework for individuals to live in peace with their fellow citizens. When a person violates the law, they are breaking the public trust and it is up to the authorities to punish them.