What makes a website an e-Commerce website?

is the buying and selling of goods and services, or the transmitting of funds or data, over an electronic network, primarily the internet.

In other word e-commerce sites are sites that are basically online retail stores. You can create your own ecommerce site with Oberlo and Shopify. The ecommerce trend as of now is dropshipping you may ask what is dropshipping Dropshipping is a service offered by (some, not all) Wholesalers. When you use a Wholesaler who offers Drop Shipping you don't have to worry about stocking or shipping products. Instead, when you get an order from a customer, you contact your wholesaler and they ship it to your customer for you. This means you, as a retailer, can sell a variety of products without ever having to stock any inventory whatsoever. This makes drop shipping very appealing for new, small, home-based online businesses. Hopefully this answers your question. #dropshipping #ecommerce #shopify

http://guidetodropshipping.com/what-is-dropshipping/

I would add WMS and RMA to the list- it is 2017 not 2000...