A bid request is a piece of code that contains information about the user who loads the website. It includes such data as location, gender, age, browsing history, device, etc.
The ad network decides what ads to display to the user when the latter is waiting for the website to load. It sends information about the users to available advertisers, chooses who may be interested in them, and chooses the brand that has placed the biggest bid. It all happens automatically in under a second.
Bid requests create a win-win situation for everyone: advertisers are able to reach only the users that may be interested in their brand and users can avoid ads that are not relevant for them.
However, sometimes users do not want to share information about them and disable data sharing to ad networks. By doing so, they are disabling the personalized ads and will get only the contextual ones. Therefore, a bid request will contain only information about the page content that the user is about to see. The advertisers with products relevant to the content will participate in the auction then.
