Which of the following best describes eCommerce?

eCommerce is fundamentally defined as the process of buying and selling goods and services via the internet. This includes various transactions that occur digitally, such as online retail, digital payments, and even marketing activities that happen online. The description of selling digitally or electronically encompasses the core activities of eCommerce, making this choice the best representation.

The other choices represent different concepts. Exchanging products in physical stores pertains to traditional retail methods rather than online transactions. Providing services without a physical location could relate to various service industries but does not specifically encompass the buying and selling of goods. Using marketing analytics involves the analysis of data to improve business decisions, which is a component of business strategy but not a definition of eCommerce itself. Thus, the focus on digital transactions in the correct option captures the essence of what eCommerce is all about.