A bid request is a function that is activated when a user visits a web page that contains ad units. It then retrieves ads from ad networks to populate the specific ad units for a specific user.
A bid request includes information about the following inventory parameters: platform, time of impression, and user data keys (IP, pixel tags, cookies), among other things.
The bid request code tries to gather as much relevant information as it can to pass on to potential advertisers. The following are some examples of data that can be obtained from a bid request:
The time of impression indicates when the user actively sees the advertisement.
User demographics give any known information about the consenting user (gender, location, age, etc.).
Browsing history offers information about previous websites visited to help advertisers target adverts based on anticipated interests.
Page data, including content and statistics pertinent to ad value.