Why is affiliate marketing a favorable form of marketing?

Affiliate Marketing has advantages for sellers as they save a lot of money on advertising costs. Affiliates come to the sellers, sign up, then market their products. The seller pays them a set commission on each sale. The seller has complete control over the costs associated with the their affiliate program in that they are simply paying set commission per sale.

For marketers, it gives them access to countless products they can sell or market from their websites or other marketing avenues. They don't have to worry about inventory, they simply use their affiliate link to make the sale and the seller ships the product. It's a win-win.