Law is defined in various ways but generally refers to a system of rules that regulates behavior and is enforced through social institutions. The document discusses different perspectives on law, including definitions from legal theorists like Jean Jacques Rousseau, John Austin, HLA Hart, and Roscoe Pound. It also outlines the key functions of law in guiding activities, enforcing rules, and maintaining order and justice. The sources and evolution of law are explored, such as through custom, religion, judicial decisions, and legislation. Different types of law are also introduced, including public law, private law, substantive law, and procedural law.