How an Excel works?

Like other spreadsheets, Microsoft Excel has a grid with a mix of data and formulas. The formulas are interpreted, which is to say they are evaluated after plugging in their inputs.

Plugging in the inputs requires that Excel parse the formulas into tokens. Each token represents either a value, operator, function name or cell address reference. Once the formula has been tokenized, the calculation engine evaluates the token chain to get the result of the formula. In some cases (IF functions being a good example), it is not necessary to evaluate the entire formula if it’s inherent logic is satisfied by the first part of the formula.

When spreadsheets first came out, the grids were small and every cell was recalculated after each change. As the number of rows and columns increased, CPU speed couldn’t keep up and people began noticing annoying delays while the formulas recalculated.

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