ADsense policies and how it works in short

Adsense is the service provided by google to its publishers to earn money by placing ads on their blog.Adsense provides you ads according to your website content. For example:if you have a blog or publishes about health issues then you will get ads of exercising tools machines,about various therapies etc.
Adsense provides you money by cost per click method,that means as many visitors click on your ads you get that much money.