is a Google service for website publishers to use for displaying text or display ads on their website. When a website visitor clicks on a Google Adsense ad, the website owner earns a percentage of the amount that the advertiser paid to run the ad. Don't try adding Adsense to your own website and clicking the ads yourself to earn money - that is against the rules and Google can EASILY tell if you are doing that. It is called click fraud
, and you should not risk losing your Adsense account for doing something so dumb.