ROI is a performance measure used to evaluate the efficiency of an investment or to compare the efficiency of a number of different investments. To calculate ROI, the benefit (return) of an investment is divided by the cost of the investment; the result is expressed as a percentage or a ratio.
I searched ROI on Google, this was the first result: http://en.wikipedia.org/wiki/Return_on_investment Could you really not have done that yourself?
This is a marketing forum right, I would of expected atleast ONE post about it. So why not, people get tired of looking on google with millions of tabs open to different google pages...
It would have been vastly quicker and more efficient to Google it. You wont be successful in this industry (or any industry) if you can't complete simple tasks on your own.
This is probably a good way to get a few more fractions of a cent through the AdSense revenue sharing. define ROI in Google always works well.