Buying or selling goods over the Internet is called:

The term that defines the buying or selling of goods over the Internet is e-commerce. E-commerce encompasses various online transactions, allowing consumers and businesses to buy and sell products and services digitally. This includes everything from retail sites where users can purchase items directly to auction sites where sellers can list goods for potential buyers.

In contrast, e-business refers to a broader concept that encompasses not only online buying and selling but also all aspects of running a business online, which includes customer service, supply chain management, and other operational processes. An intranet is a private network accessible only to an organization's staff, primarily used for internal communications rather than commerce. An extranet extends a company's intranet to outside users, such as suppliers or partners, allowing them limited access to certain company resources but does not pertain to the sale of goods online.

Thus, e-commerce specifically captures the essence of buying and selling goods over the web, making it the correct term for this practice.