Bitcoin affiliate programs allow affiliates to gain revenue by driving traffic to specific Bitcoin related programs. The revenue is paid in a CPA (cost per action) or Revenue Share model depending on the program. Although most Bitcoin affiliate programs pay their affiliates with Bitcoins, several programs pay their affiliates with fiat. Make sure to follow best ethics when applying to an affiliate program
Bitcoin affiliate programs are a great way to make passive income if you run or are involved in a website (or anything else on the web that gets visitors). Services that run Bitcoin affiliate programs will pay you in bitcoins if you send them paying customers. It works like this:
You sign up for the service's affiliate program and give them your Bitcoin address.
The service gives a unique referral URL that points to their website.
You post the URL on your own website, Facebook, a forum signature, tweet it, whatever.
Someone clicks your referral link, and then makes a purchase on the service's site.
The service sees that you sent them that there customer, and you earn a commission on the purchase. That means you get paid by the service, in bitcoins!
The more people that click link, the higher the chance that you'll make some decent money. Which means getting a whole shitload of internet traffic is the key part to making any kind of serious money with affiliate programs.