Second paragraph of the Google 2004 financial report (first paragraph described what Google is):
We generate revenue by delivering relevant, cost-effective online advertising. Businesses use our AdWords program to promote their products and services with targeted advertising. In addition, the thousands of third-party web sites that comprise our Google Network use our Google AdSense program to deliver relevant ads that generate revenue and enhance the user experience.
Google has been an ad company way before 2013.
AdWords was launched in 2000. Google bought DoubleClick in 2007. https://en.wikipedia.org/wiki/DoubleClick
Second paragraph of the Google 2004 financial report (first paragraph described what Google is):
https://www.sec.gov/Archives/edgar/data/1288776/000119312505...