ROI means return on Investment. Return on investment is important indicator which is used to measure the efficiency in business. Its calculation is similar to that of calculation of interest on Fixed Deposit. For Example if i want to invest $10000 in Fixed deposit for a period of a year @9% simple interest then i would get $900 as Interest. That amount which is received as interest is Return on investment of $10000. Entrepreneur is not interested on how much profit earned but he is interested on how much ROI he has received on investing certain sum in the business.