This document defines and describes different types of e-commerce. It explains that e-commerce involves the buying and selling of products or services over electronic systems like the internet. The main types of e-commerce discussed are business-to-business (B2B), business-to-consumer (B2C), business-to-government (B2G), and consumer-to-consumer (C2C). It also covers mobile commerce (m-commerce) and provides examples of common business applications that relate to electronic commerce.