Law is the body of rules enforced by a controlling authority, such as the government. Laws can be moral or immoral and they can vary widely in their application. They can be specific or vague, and they can cover everything from the specifics of contract law to medical jurisprudence. Laws can also be based on religion or written down in books like the Jewish Halakhah, Islamic Sharia and Christian Canon law.

A key question is what distinguishes a law from mere suggestions or good advice. For example, if someone says that you should “eat five fruits and vegetables a day,” it’s not likely that anyone will punish them for not doing so. However, if someone breaks the law by stealing or embezzlement, they may be arrested and prosecuted under criminal law.

The law is a vast and complex field. Many people specialize in particular areas of the law, and careers as lawyers are becoming increasingly popular. Different legal systems differ, and the law is constantly changing in response to new needs, technology and social developments. The law covers all aspects of human activity, from the rights and responsibilities of people in their families to the rights of corporations. It can also include the rights of nations in their international relations. It can even be applied to science, with laws on intellectual property and environmental protection. The laws are set by a variety of institutions, including the judiciary, executive and legislative branches of the state.