How do those E-commerece websites that have no inventory make money?

I don't understand. Does it have to do with retail or something ?

I don't understand the question? If they have absolutely nothing on their website then they are not making any money; they would be technically losing money.

These websites don't really need an "inventory" to make money. These websites can be an online broker service, making and/or having online advertisements from other companies. They can even be a payment gateway where one website such as Amazon is using a controlled server from an e-commerece website.

Example: If Amazon is using someone elses server and a person adds $50.00 worth of merchandise in their "cart" and then let's say 80% of the funds goes to the seller, then the other 20% goes to amazon for selling their item. Now amazon has to pay 8% of their profit from that purchase to the server they were using. That also counts as e-commerece.

Hopefully I explained that well enough.