E-commerce typically refers to buying and selling goods and services online, but there is more to it than that. E-commerce is widely considered the buying and selling of products over the internet, but any transaction that is completed solely through electronic measures can be considered e-commerce. E-commerce is subdivided into three categories: business to business or B2B, business to consumer or B2C, and consumer to consumer or C2C, also called electronic commerce.

There’s lots of money to be made online, but not all of this involves selling goods in the traditional way. Many online businesses try to make money by offering a mixture of free and premium services. Created as a comprehensive directory of other websites, it mutated into a search engine and then a portal, offering a gateway to all kinds of other premium services. For example, you can get free e-mail through gmail, but you can also pay extra for a more sophisticated e-mail system; you can store your photographs for free on Flickr site, but you can pay an extra sum to have them printed out or processed in various ways.

Newspapers, magazines, and book publishers also try to make money through a mixture of free and premium services. While most of them offer their basic content for free, using advertising to make money, some also offer a proportion of their articles for a one-off fixed fee or subscription. Buying an article involves a transaction similar to the ones you’d make on Amazon or eBay, so this kind of online publishing is also clearly a variety of e-commerce.