What are the profit models of e-commerce?

At present, the profit models of e-commerce are: 1, membership fee, 2, advertising fee, 3, bidding advertising fee, 4, booth fee, 5, logistics fee, 6, storage fee, 7, processing fee if there is deep processing. The B2C platform for selling books you mentioned, let's take Dangdang as an example. Its profit model is (1) direct selling, which lowers the price of manufacturers (retailers) and earns the difference between the purchase price and the selling price. (2) Virtual store rental fee, product login fee and transaction fee; In addition, we can also use the platform to make full use of the huge constant funds generated by the time difference between payment and receipt to obtain other investment profits in reverse. (3) Advertising expenses