E-commerce refers to the buying and selling of goods and services online. It allows companies to reach customers worldwide through online searches, websites, and email marketing. Different types of e-commerce business models include bricks-and-mortar stores that also sell online (multichannel) and businesses that only sell products and services via the internet (e-tail). The reading discusses key vocabulary for e-commerce and provides examples of zero, first, second, and third conditional sentences to describe different hypothetical scenarios related to business and marketing online.