When a website subscribes to Google Adsense, a bot (robot/program) will ‘crawl’ the content on your page and find keywords. Base on what it finds, it will select the a few ads to be published on that site.
Example: if you are stupid and reading a website about your condition, the word ‘stupid’ will obviously (not obvious if you’re stupid) appear a few times. Thus, all ads that appear on that site, will be related to Stupid, stupidity and/or you.
I was on my Gmail yesterday. The email I opened was from Germ regarding the poster for RandomAttire.
To my intelligent surprise (not sure what word in my emails sparked this), but one of the four ads that appeared read,
.
Faraj Lebih Ketat
Atasi faraj longgar dan berair.
Suami pasti puas. Dijamin. RM67.00
www.isteriperkasa.com