ROI is a measure of return on investment. It is calculated by dividing the profit generated by an investment over a given period. The ROI model is a useful tool for businesses to help them determine whether or not their investments are worth it. It provides a way for businesses to compare different alternatives and choose the one that has the best return on investment. The ROI model helps companies decide how much they should invest in an idea, what type of business model will be best for their company and how long they should wait before seeing any profits from that investment.