An array is a type of formula that can perform multiple calculations on one or more items in an array . You can think of an array as a row of values, a column of values, or a combination of rows and columns of values. Array formulas can return either multiple results or a single result. Advantages of arrays are:
Consistency & Accuracy: If you click in any of the cells with an array formula, you see the same formula.
Safety: You cannot overwrite a component of a multi-cell array formula, since it applies to all the cells in the array.
Smaller file sizes: You can often use a single array formula instead of several intermediate formulas, saving storage space.