ummmm cookies how come certain adverts know what sort of thing i want to buy. such as the one on this page it keeps telling me i can get 50% off brake disks haha is there some sort of third party that can access my cookies (ummm cookies) and display advertisements as necessary?
There are a few ways that smart ads can happen. And a lot of complex variations of all the following and more. First, as you guessed, is cookies. "Hey amazon says you've been looking at video games. You might like video games. Do you think this one looks cool?" Although since cookies are rarely that readable to anyone that didn't write them some sites will rely on tracking cookies for that. Second is by a database look up. Similar concept but it is all done server side. So clearing cookies, or even going to a new computer, won't change the ads so long as you signed into whatever account it is. This is a huge one for Google. Third isn't as smart, but site context often plays a role too. For example here on KHV a major group interest is videogames, so those types of ads would get more clicks here and thus be displayed more often. Though some of the dumber algorithms for context ads can have rather humorous results; like when the ads would change to couch shopping when a member here "La Sofa" would post. It looks like KHV is done through Evidon, which would use a combination of cookies and site context. And if you find the whole tracking thing to be freaky there is an opt-out (click the blue triangle in the corner of an ad) and you could use a program like Ghostery (interestingly made by Evidon) to stop tracking cookies and other privacy risks. Notably on the opt out for Evidon's interest based ads, the decision is stored as a cookie. Meaning that if you clear your cookies then you will be opted back into the service by default.
In addition to what Mixt says, if the ads are powered by Google's Adsense service (ours are), it will take into account your recent search history (if you've set up Google to store your search history). So if I spent hours googling puppies and beanie babies, I'd have some ads for the two.
Thats better, at least i know its google thats stalking me and not some crazy life stealing Philippine :)
