
Apply data validation to cells - Microsoft Support
Use data validation rules to control the type of data or the values that users enter into a cell. One example of validation is a drop-down list (also called a drop-down box or drop-down menu). Watch more in this video.
More on data validation - Microsoft Support
You can use data validation to restrict the type of data or values that users enter into cells. 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.
Add, change, or remove data validation - Microsoft Support
Add data validation. Change a data validation condition. Remove data validation. Ways that users are notified about validation errors. For a form that is designed to be filled out by using InfoPath, you can set a data validation message to be displayed as a ScreenTip.
Add or remove items from a drop-down list - Microsoft Support
Go to Data > Data Validation. On the Settings tab, click in the Source box, and then on the worksheet that has the entries for your drop-down list, Select cell contents in Excel containing those entries. You'll see the list range in the Source box change as you select.
Create a drop-down list - Microsoft Support
You can insert a drop-down list of valid entries (also called a drop-down menu or drop-down box) in Excel to make data entry easier, or to limit entries to certain items that you define.
Find cells that have data validation rules - Microsoft Support
You can find cells in a workbook that contain data validation by using the Go To Special dialog box. On the Edit menu, point to Find, and then click Go To. Click Special. Select Data Validation. To find all cells with data validation, select All, and then click OK.
Remove a drop-down list - Microsoft Support
To remove a drop-down list, click the cell with the list, then click Data > Data Validation, and then on the Settings tab, click Clear All, then OK. A drop-down list is also known as a drop-down box or drop-down menu.
Display or hide circles around invalid data - Microsoft Support
You may want to use the data validation tools to check your worksheets for incorrect data that may cause inaccurate calculations or results. Cells that contain invalid data appear with a red circle around them so that you can easily find and correct any problems.
Restrict data input by using validation rules - Microsoft Support
You can use the Validation Rule property and the Validation Text property of a form control to validate data that is input to that control and to help users who input data that is not valid.
Make a control required - Microsoft Support
On the Format menu, click Data Validation. Click Add . In the first box under If this condition is true , click Select a field or group , and then select the field or group that the control is bound to.