In the world of Boolean algebra, there are only two possible values for a math operation: 1 or 0. Boolean logic refers to a technique of building formulas to take advantage of the fact that TRUE = 1, and FALSE = 0. In Excel, any math operation will coerce TRUE and FALSE values into 1's and 0's. In the example shown:
Boolean logic can be used to simply formulas and eliminate the branching seen in nested IF formulas. In the example the formula in E5 is equivalent to:
Boolean logic often shows up inside other formulas and functions. The SUMPRODUCT function is a good example. To count cells in A1:A10 that are equal to "red" with SUMPRODUCT, you can use a formula like this:
The double negative coerces the TRUE and FALSE values that result from the expression A1:A10="red" to 1s and 0s, and SUMPRODUCT then returns the sum of these numbers, which corresponds to the count of cells that contain "red".