Affiliation
A merchant, also known as an advertiser or a retailer, is a website or company that performs online sale of a product or a service, accepts payments, and fulfills orders.
Affiliates, also called publishers, place ads, text links, or product links of merchants on their websites, shopping engines, blogs, etc. or include them in e-mail campaigns and search listings in exchange for commissions on leads or sales.
Merchants acquire new customers and pay affiliates only when a sale or other qualifying action is performed. This is called cost per action (CPA) or performance-based marketing. 
