This document provides an introduction and definitions for key economic concepts. It begins with defining economics as the management of household according to its Greek roots. It then summarizes the different definitions of economics provided by Adam Smith, Alfred Marshall, and Lionel Robbins. Smith defined it as the science of wealth, Marshall shifted to welfare, and Robbins emphasized scarcity. The document also briefly outlines the main divisions of economics and basic concepts like goods, utility, wants, value, price, markets, and income.