Google recently announced that Adsense for Domains is now using optional keyword hints more often Keyword hints are given by the user who enters the keywords to help Google in ad targeting for ambiguous domains.
The keywords are suggestions given to Google by domain owners regarding the the type of content users are seeking when the arrive on a less than developed domain. These keyword hints are used to help Google determine what ads to place on the domains.
It is optional to use keyword hints. When a publisher provides keyword hints the ad matching system will make use of them more frequently. Google aims to give users the most relevant ads and the best returns for online publishers.
If you would like to learn more about this, go to Adsense for Domains website to read all of the details. Many Adsense users have complained in the past that many of the ads that Google places on their site are only vaguely related to the site’s content. The keyword hints should help to make the ads more relevant.