This document discusses e-commerce (electronic commerce). It defines e-commerce as the buying and selling of goods and services over electronic networks, primarily the Internet. It describes the different models of e-commerce including business-to-business (B2B), business-to-consumer (B2C), business-to-government (B2G), and consumer-to-consumer (C2C). It also discusses the necessary technologies and infrastructure to support e-commerce such as networks, web servers, electronic catalogs, and payment systems.