Here's how most affiliate marketers operate:

They have a website in a particular genre, such as health and fitness, coffee products, cameras, golf, jewelry, children's clothing etc.

They find appropriate vendors with an affiliate program and get approved as an affiliate.

The vendor supplies them with links to their products. The affiliate marketer promotes the products through blog posts, direct email or paid advertising. Each product promotion contains the vendor link for that product.

When a customer clicks on the link, they are taken to the vendor's website. If they purchase the product, the affiliate marketer is automatically paid the commission.

In the process of making the sale, the vendor collects the customer's details. So the vendor ends up with a potentially long-term customer while you, who did all of the promotional work, don’t.