Perhaps the simplest way to explain affiliate marketing is that it is a way of making money online whereby you as a publisher are rewarded for helping a business by promoting their product, service or site.
There are a number of forms of these types of promotions but in most cases they involve you as a publisher earning a commission when someone follows a link on your blog to another site where they then buy something.
Other variations on this are where you earn an amount for referring a visitor who takes some kind of action – for example when they sign up for something and give an email address, where they complete a survey, where they leave a name and address etc.
Commissions are often a percentage of a sale but can also be a fixed amount per conversion.
Conversions are generally tracked when the publisher (you) uses a link with a code only being used by you embedded into it that enables the advertiser to track where conversions come from (usually by cookies). Other times an advertiser might give a publisher a ‘coupon code’ for their readers to use that helps to track conversions.