This is the most popular payment offered by most of the affiliate programs. Under this program, the affiliate marketers earn commissions from the merchant each time they will send a client to the merchant website, and that client makes an actual purchase. Various affiliate programs offer a specific percentage of the sale as commission while others will pay you a fixed rate for every sale.
The problem with affiliate marketing, like many other home business options, are the so-called gurus and get-rich-quick programs that suggest affiliate marketing can be done fast and with little effort. Odds are you've read claims of affiliate marketing programs that say you can make hundreds of thousands of dollars a month doing almost nothing ("Three clicks to rich!"). Or, they suggest you can set up your affiliate site, and then forget it, except to check your bank deposits.