E-commerce sites make money through various revenue streams. Here are some common ways they generate income:

1. Selling Products: The primary source of revenue for e-commerce sites is selling products directly to customers. They offer a wide range of products, including physical goods, digital downloads, services, or subscriptions. E-commerce platforms act as intermediaries between sellers and buyers, facilitating transactions and earning a commission or a percentage of each sale. For example, Amazon charges sellers a referral fee ranging from 6% to 45% based on the product category.

2. Advertising and Sponsorships: E-commerce sites often generate revenue through advertising and sponsorships. They can display ads on their platforms, such as banner ads, sponsored content, or native advertising. Advertisers pay to have their products or services showcased to the e-commerce site's audience. For instance, Alibaba's e-commerce platform, Tmall, offers various advertising options to brands looking to promote their products to millions of users.

3. Subscription Fees: Some e-commerce sites offer premium memberships or subscriptions that provide additional benefits to customers. These can include perks like free shipping, exclusive discounts, access to special events, or early access to new products. By charging a recurring subscription fee, e-commerce sites can generate a steady stream of revenue. For example, Amazon Prime offers a membership program that provides various benefits for an annual fee.

4. Dropshipping: E-commerce sites can also make money through dropshipping. In this model, they partner with suppliers or manufacturers who handle the inventory and shipping processes. When a customer places an order, the e-commerce site transfers the order details to the supplier, who then fulfills the shipment directly to the customer. The e-commerce site earns money by charging a markup on the product price. Shopify, a popular e-commerce platform, supports dropshipping integrations and allows entrepreneurs to set up their own dropshipping stores.

5. Affiliate Marketing: E-commerce sites can earn revenue through affiliate marketing by promoting products or services from other companies. They include affiliate links on their platforms, and when a customer clicks on those links and makes a purchase, the e-commerce site receives a commission. For example, websites like Wirecutter or PCMag provide affiliate links to products they review, and if a user buys the product through their link, they earn a commission from the retailer.

6. Data Monetization: E-commerce sites collect vast amounts of customer data, including purchase history, browsing behavior, and demographics. They can monetize this data by selling it to third parties, such as market research firms or advertisers. By leveraging customer insights, these companies can improve their marketing strategies or develop new products. However, it's crucial for e-commerce sites to ensure data privacy and comply with applicable regulations.

References:
- Amazon Referral Fees: https://sell.amazon.com/pricing.html
- Alibaba Tmall Advertising: https://www.tmtpost.com/4190190.html
- Amazon Prime: https://www.amazon.com/amazonprime
- Shopify Dropshipping: https://www.shopify.com/dropshipping
- Wirecutter: https://www.wirecutter.com/about-us
- PCMag Affiliate Program: https://www.pcmag.com/affiliate-program