Return on Investment (ROI) is a financial metric used to evaluate the efficiency and profitability of an investment. It measures the return on an investment relative to its cost. By calculating ROI, businesses and investors can assess the potential benefits and risks of investing in a project, purchase, or financial product. ROI is a universal measure, making it easy to compare the effectiveness of different investments.

For example, a company might calculate the ROI of a digital marketing campaign by comparing the additional revenue generated directly from the campaign to its cost.