An affiliate program refers to the modern, web based equivalent of an old concept. In the past businesses have paid other groups or businesses finders fees for recommending their service. Web based affiliates work on this principle.
Company A will ask that company B has an advertisement for their website (site A) included on their website, site B. So when people viewing site B see the advertisement for site A and go on it, company B earns money from company A as reward for providing them with customers.
With online business this payment is commonly done based on the amount of times that an advertisement is clicked on by customers. When the user clicks an advertisement banner and is redirected to the advertised site, it is recorded and an agreed amount of money is given to the site hosting the advert, per click. Many sites are very open about this and will state that the following advertisements are affiliates and that to show support for their site, please click the advertisement at least once, providing them with the funds to continue running the site. The great benefit of this method is that the advertiser only pays for each actual customer referred to them,...