Affiliate programs are programs that companies setup to allow you to refer business to them and receive commissions on orders placed by referred customers. Affiliate programs are a lucrative way to earn revenue and / or receive the service of the business you are referring at no charge.

For example: I currently refer Audio Acrobat as one of the tools that I use to store and distribute my audio programs. Since I have referred so many people to the tool via my affiliate link, I have not paid for the service in four years. I also have earned over $2,500 in affiliate commissions simply by referring a service that I use and love.