Amazon is changing a policy on affiliate links to free Kindle books, and the changes are likely to have a big effect on the way some self-published authors achieve success online.

In the last few years, entire websites aimed at promoting free Kindle books have sprung up. Their business model is primarily referral fees: When a visitor to one of these sites clicks on a link to Amazon to download a free ebook, but then buys other products on Amazon within 24 hours, the original site gets a percentage of those unrelated paid sales.