For a firm, gross income (also gross profit, sales profit, or credit sales) is the difference between revenue and the cost of making a product or providing a service, before deducting overheads, payroll, taxation, and interest payments. This is different from operating profit (earnings before interest and taxes). Gross margin is often used interchangeably with Gross Profit, but the terms are different. When speaking about a monetary amount, it is technically correct to use the term Gross Profit; when referring to a percentage or ratio, it is correct to use Gross Margin. In other words, Gross Margin is a percentage value, while Gross Profit is a monetary value.