This document provides an introduction to key concepts in marketing, including: 1. The relationship between buyers and sellers, where buyers depend on sellers for goods and services they want and sellers depend on buyers for profits. 2. Definitions of markets, consumers, customers, and commercial markets. 3. The concepts of product orientation versus market orientation. 4. The key elements of promotion, advertising, public relations, publicity, and sales. 5. How needs, wants, and demands differ. 6. Several definitions of marketing and its core purpose of identifying and satisfying customer needs profitably.