This document provides an introduction and summary of H.L.A Hart's theory of law, which distinguishes between primary and secondary rules. Primary rules directly govern human behavior by imposing obligations or granting rights. Secondary rules determine how primary rules are recognized, changed, and enforced. According to Hart, secondary rules are necessary to remedy uncertainties, static nature, and inefficiencies in a system composed solely of primary rules. Primary rules examples include freedom of speech and environmental regulations. Secondary rules examples include contract formation rules and rules governing wills. The document concludes that while the researcher was correct to distinguish primary and secondary rules, other jurists have criticized Hart's theory and proposed alternative perspectives.