When working with Excel formulas, a common term is "empty string". A text string is a text value like "apple". An empty string is a text value that has no value. Since text in Excel formulas must be enclosed in double quotes, an empty string appears as empty double quotes ("").
For example, in the screenshot shown, the formula D5, copied down, is:
Here, we use the IF function to check the value in column C5. If the value is greater than 10, the formula returns "x" as text. Otherwise, IF returns an empty string ("").
When an empty string is the result of a formula, it looks like the cell is blank. So, empty strings are commonly used to return a value that looks like nothing. In other words, return a result that appears as an empty cell.
One thing to note is that some functions will treat empty strings as if they do have a value. For example, the ISBLANK function will return FALSE if used on a cell that contains a formula that has returned "". Likewise, the COUNTA function will include cells that contain formulas that have returned "".