How does Amazon know what I was just Googling?

(light music) - Sweetie, I'm going to buy a new blender on Amazon. Do you need anything? Wait, Amazon is recommending the exact model I was just researching on Google? - Hey, how does Amazon know what I was just googling? Advertisers and other Web services want to profile you. You know those ad banners you see on various sites? Those are part of an ad network, which is why you sometimes see the same ad on different major websites. These ads gather bits of information from this site and then tie it to other information they have on other sites you visit that also use that same ad network. They know you're the same person because of your computer's IP address, so this can sometimes be awesome. - Oh, I forgot I wanted to buy that. - Or ruin things for you. - Sweetheart, have you been shopping for Christmas decorations? You better not have ordered that 35-foot inflatable Santa. - Or even annoy you. - I just bought a blender. Stop showing me blenders. - Let's suppose you looked at a site…