Amazon is a place where you can get almost anything. One of the reasons for that is that they sell products offered by other sites as well. So I wanna know how do they do that? Its one thing when you promote others' products on your pages but a totally different one when you actually show the option of "add to cart" and even accept the payment for a third party product. I hope you understood what I'm trying to say. I'll try to repeat in a more clear fashion. For example, if amazon is selling something from some random site like xyz.com. You like the product and you add it to your cart and you continue shopping and go on to add stuff from different retailers to your cart. And ultimately, you can own all those items coming from different sellers just by paying Amazon. How do they do that? Can I open a site of my own and sell others' stuff and receive payments of all of them?
Yes, you can join Amazon Associates program and promote any of the products listed on Amazon.com. You'll get paid when the products gets shipped.
They're basically taking payment for all of the items and then paying the sellers after removing their fees. It's called merchant aggregating, if you're asking about the payment side of it. There's very few merchant accounts that allow aggregating as it is very high risk, and introduces unanticipated complexity in who's accountable for a credit card or payment transaction.
Thanks for your response jestep. Their processing can be understood as far as physical products are concerned because they take time for delivery and so all the transactions can be cleared in the meanwhile but what about the others like softwares, e-books and others which are instant deliveries. You get access to that stuff on amazon even if its third party. Is there any system which automatically transfers the money to each separate vendor when buyer chooses different products?