Is Google Using AdSense PSAs for Free Advertising
When Google is not able to serve relevant AdSense ads on a web page, the system will display Public Service Ads instead of the regular ads to promote organizations like Red Cross, Direct Relief, etc.
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Google Earnings Report – Good News for AdSense Publishers?
Google doesn’t disclose the percentage of advertising revenue that it shares with AdSense publishers but you can pick some clues from their quarterly earnings data.