As with traditional commerce, there are four principal categories of eCommerce: B2B, B2C, C2B and C2C.

• B2B (Business to Business) — This involves companies doing business with each other. One example is manufacturers selling to distributors and wholesalers selling to retailers.

• B2C (Business to Consumer) — B2C consists of businesses selling to the general public through shopping cart software, without needing any human interaction.

This is what most people think of when they hear “e-commerce.” An example of this would be Amazon.

• C2B (Consumer to Business) — In C2B e-commerce, consumers post a project with a set budget online, and companies bid on the project. The consumer reviews the bids and selects the company. Elance is an example of this.

• C2C (Consumer to Consumer) — This takes place within online classified ads, forums or marketplaces where individuals can buy and sell their goods. Examples of this include Craigslist, eBay and Etsy.