Blank ads refers to the cases where ad placements are empty because ads are not showing.
Blank ads may be "displayed" when ads are blocked for brand safety reasons or when there is no advertiser available for the ad placement.
In such cases, visitors see "blank ads" because the ad tag is loaded with the page and still delimits the ad placement.
Blank ads are increasingly scarce and replaced by charity ads (public-service ads) or back-up ads. They can still be seen in the case of temporary ad serving failure.
Millions of blank ads in 2010 in India: