AdSense

AdSense is a ads program cooperation by internet from google. With AdSense program, site or blog owner who has register and approved can place a ads unit who the materi of ads is given by google at they site or blog. Site or blog owner will earn some money for profit shared from google every single click from the web visitor, this system also known as pay per click (ppc).
Beside ppc AdSense also have a program called AdSense for search and Referral. For AdSense for search, the site owner can place a google search box at their site. Site owner earn from google for every search doing by visitor from the search box, who continue to click the ads from the result of searching. From Referral, site owner get earning from google, if they approved.