Payment of affiliate programs

There are three types of affiliate program payment:

1. Pay per sale: The merchant site pays an affiliate when the affiliate sena a customer who purchases somthing.
2. Pay per click: The merchant site pays the affiliate depending on how many clicks are made to come on the merchant site. It does not matter if the visitor does not buy something.
3. Pay per lead: The merchant site pays according to how many number of visitors they refer who sign up as lead. The lead simply fills some requested information.