Law is the word used to describe a set of rules or regulations that govern the way people live in a society. These laws can be made by governments or private individuals and are often enforced in order to prevent people from breaking them.

Legal systems can serve a variety of purposes, including keeping the peace, protecting individual rights, maintaining the status quo, promoting social justice, and providing for orderly social change. Some legal systems are more effective than others at serving these purposes, but they can all be useful for their respective communities.

Common law and civil law are two of the most widely practiced legal systems, with each covering around 60% of the world. They are based on concepts, categories and rules that grew out of Roman law, with some influence from canon law, sometimes supplemented or modified by local customs and cultures.

Religion is also an important source of law. Some religious communities follow a specific set of laws and practices, called jurisprudence, which can be very detailed. Examples include the Jewish Halakha and Islamic Sharia, both of which are based on the word of God.

Depending on its source, religion can either be incorporated into the law as a rule, or it can be an inspiration for further legal reasoning through interpretation (Qiyas, Ijma and precedent) which are also known as fiqh. Some Christian churches have canon law which they follow.

The Will (or Choice) Theory of rights, argues that right-holders have the power to control as a matter of choice which duties are owed to them or not, and what is required of them. They have the Hohfeldian power to annul, waive, transfer, or enforce these duties, and they also have the Hohfeldian privileges and powers to exercise them as they choose.