An Inquiry into the Nature and Causes of the Wealth of Nations, usually referred to by its shortened title The Wealth of Nations, is a book by Scottish economist and philosopher Adam Smith. Published on 9 March 1776, it offers one of the first accounts of what builds nations' wealth. It has become a fundamental work in classical economics, and been described as "the first formulation of a comprehensive system of political economy". Reflecting upon economics at the beginning of the Industrial Revolution, Smith introduced key concepts such as the division of labour, productivity, free markets and the role prices play in resource allocation.