How Adsense Work?
AdSense allows you to paste a small amount of code on your web pages which reads various on page and off page topics to determine what the page is about. Automatically AdSense will usually serve relevant ads to the page copy. AdSense allows you to split the ad revenue from these ads with Google. If AdSense can not determine what the page is about they will place public service announcement ads or alternate ads of your choice.
Who is Adsense for?
Generally AdSense is for larger content websites. If your site is purely commercial in nature it is harder to get accepted to AdSense. Qualifying for AdSense should not be that hard though, as most commercial websites should provide more than just a commerce platform.
The web was created to allow the free flow of information. I am exceedingly more likely to buy off a person who provides details about their services or products. Unbiased reviews, free information, and user feedback gain credibility with your user, which will allow you to further expand your marketing leverage while increasing your pages views and your ad revenue.