Excel's Data Validation command lets you perform validation on entries to set up data validation rules. You can define data that is acceptable for any given cell or range of cells, and input messages or error alerts that display whenever a validated cell is selected. Error alerts can display whenever a validated cell is selected or when a user tries to enter an invalid value. Data Validation only warns you against inputting invalid data—it doesn't stop you from doing so.
Follow the steps in the next exercise to set up the data validation rules. You are setting rules for the Car data in column B on the Detail sheet.
Click cell A12 on the Detail sheet. Type New York and press ...