Note: This is an advanced topic on data validation. For an introduction to data validation, and how to validate a cell or a range, see Add data validation to a cell or a range . You can use data validation to restrict the type of data or values that users enter into cells. For example, you might use data validation to calculate the maximum allowed value in a cell based on a value elsewhere in the workbook. In the following example, the user has typed abc , which is not an acceptable value in that cell. When is data validation useful? Data validation is invaluable when you want to share a workbook with others, and you want the data entered to be accurate and consistent. Among other things, you can use data validation for the following: Restrict entries to predefined items in a list — For example, you can limit a user's ...