For example, I build a extension or w/e of maybe even a website about gaming. I also have an affiliate link to a site that sells the game for crazy cheap. (legit, no scams) The website will show up a review on a game, with the link to the website/websites to buy this game with prices etc. But the website also upon entering puts cookies into your browser that "hold" my affiliate codes. Same goes for an extension. For example a extension on something stupid that silently installs cookies with amazon affiliate link into your browser. Can this be done and most importantly is it legal?