An Excel formula is an equation or calculation that is stored in a worksheet cell. A formula enables you to perform simple or complex calculations on numbers — any scenario involving addition, subtraction, division, or multiplication.
Functions are built-in formulas programmed to perform a specific calculation, ranging from simple ones like SUM and AVERAGE to the more powerful IF and VLOOKUP. Functions aren't limited to numeric data either — they can save you a ton of time working with text and dates too.