Law is a system of rules, usually enforce through a set of institutions. It shapes politics, economics and society in numerous ways. Contract law regulates everything from buying a bus ticket to trading swaptions on a derivatives market. Property law defines rights and obligations related to transfer and title of personal and real property, for instance, in mortgaging or renting a home. Trust law applies to assets held for investment and financial security, such as pension funds. Tort law allows claims for compensation when someone or their property is injured or harmed. If the harm is criminalised in a penal code, criminal law offers means by which the state prosecutes and punishes the perpetrator. Constitutional law provides a framework for creating laws, protecting people's human rights, and electing political representatives. Administrative law relates to the activities of administrative agencies of government. International law regulates affairs between sovereign nation-states in everything from trade to the environment to military action. "The rule of law", wrote the ancient Greek philosopher Aristotle in 350 BC, "is better than the rule of any individual."