A common use of data validation is to create a drop-down list. Use it to restrict the type of data that users enter into an Excel cell.

On the Data Validation dialog, choose the criteria you want to use in the boxes on the Settings tab. Go to the Input Message tab and enter the message you want users to see when they click in the ...

Data validation is one of the most effective ways to protect Web applications from attack. Ensuring only the data you expect is entered into a form or provided via some other input mechanism ...