This is seen in the form of several types of ad-space...be it banner ads, text ads or combination of both and it is given in return for purchasing from a sponsor and from the admin of the program.
Some know this form as 'randomizer' while if I could re-invent the wheel...I'd prefer to call it 'equalizer'!
You see...what happens when a marketer places an ad on one of these sites, two exciting things begin to take shape.
One. That marketer will (usually) BLAST that web-page containing their ads AND possibly other ads placed by a different advertiser in rotation.
Two. If the person markets the page enough and is successful, they can make some really nice change back PLUS gain all that exposure to their website links in the meantime.
I have only one problem with a randomizer that has a members ads in rotation...it is STILL a hit and miss situation as far as exposure to their website links.
Reselling a POSITION in a randomizer is ALWAYS a hit and miss situation just like most other reseller programs.
However...armed with that similar type of insight... some very smart coders decided to Re-Invent the randomizer, and taking OUT that hit and miss situation, simply by allowing the script to display a users ad, banners and or video clips right there on their OWN copy of the website page.
And if that wasn't enough, they decided to turn the traditional boring randomizer into a Matrix style system where multiple folks could benefit just by the efforts of each ONE person!