In a disturbing form of Integration period advertising technology, advertising firms and networks formed a way to keep track of those who came within proximity of their madverts and advertising forms. The displays projected a small cloud of nanodevices that adhered to the skin, hair, clothing and personal property. These "nanowatchers" then tracked other advertising memes encountered and tailored future ads to combat previous ones the sophont has seen.
Nanocookies went a step further and tracked other purchases and expenditures to better target ads to attempt to foster "buyer's remorse" or dissatisfaction with competitor's products that were recently purchased. Although some polities banned nanocookies, it proved hard to stop them. Often they traveled and followed a person through many systems monitoring events there. More restrictive, libertarian, totalitarian and paranoid polities went so far as to employ blue goo technology at ports of entry to scrub what they considered "spyware" from traveler's belongings and bodies. Some merchants, government facilities and corporate offices were forced to include cleansing systems to prevent spying by this means as well.
This form of marketing is still often employed on more traditional NoCoZo-affiliated angelnetted worlds, corporate stations and systems, and certain non-transapient-ruled free zones where the free market has run amok. It is not used as much, today, as during the Integration, but is still seen by some polities as an effective way to market and control market pressures. Many groups who believe in the right to privacy are known to have committed subversive acts against nanocookie dispensing adverts in the form of vandalism and even attacks on corporate property in response to the market tracking.