An opt-out cookie is set by an ad network on a user’s desktop for registering the fact that a consumer does not want to be targeted according to his past browsing behavior.
The cookie has a code value that tells the ad network server not to do interest-based targeting. An opt-out cookie does not stop ad serving but only behavioral targeting.
It is a paradox that the consumer must accept a cookie for opposing tracking.
Opt-out cookies are often denounced as being ineffective as they can be unwillingly deleted or the opt-out process has to be made again if one change the browser or the computer.
For the first reason, some actors offer browser plugins dedicated to opt-out.
Below, Network Advertising Initiative enables on a single page to verify the presence of cookies of more than 70 players in behavioral marketing and to practice the opt-out.