Law is a system of rules and principles that regulates human behaviour. It has many aims including keeping the peace, maintaining status quo, protecting individuals, preserving minority rights against majorities, promoting social justice, and providing for orderly social change. Different legal systems achieve these goals in different ways.

The main purpose of law is to provide a common standard for behaviour across society. The standard is established by laws that set out what is considered acceptable and unacceptable in different situations. These laws may be written or unwritten. The most common law is written and includes statutes, regulations and case-law (judgments of a court).

Another important function is to provide a mechanism for people to resolve disputes. Disputes may be about the possession of property, contracts or debts. This is achieved through a legal system of courts and arbitrators who hear cases and make decisions. The underlying principle of the legal system is that all parties are treated equally, regardless of their status or ability to pay.

Other laws regulate specific types of activity, such as the regulation of certain industries like energy, water or telecommunications. The law may also deal with personal matters, such as marriage and divorce or the rights of children and parents. It is often based on religious precepts, such as the Jewish Halakha and Islamic Sharia, or the Christian canon law that survives in some church communities.

Lastly, the law provides an official record of the transactions and relationships of society that are recorded in the public domain. It is also a source of scholarly research into the history, philosophy and sociology of law.