US Federal Trade Commission, as well as many other governing bodies across the globe, have strict sets of rules regarding the information that can influence investment decisions. Companies are obliged to release all the details that would help viewers and readers determine whether their opinion is biased. So, if a publisher is getting money or gifts for promoting a certain brand, they need to make it clear to the visitors. What this means is that any affiliate link you might have on your site needs to be publicly disclosed, as a way of preventing the conflict of interests. The same goes for Google AdSense ads and direct ad sales, as well.