A drop-down list is a great way to ensure that your users enter data that is consistent with what you are expecting. By providing a list of valid entries, you can prevent errors and improve the overall quality of your data. Excel makes it easy to create a drop-down list, and you can even make a single-use drop-down list that will only be used once and then deleted.
To create a single-use drop-down list in Excel:
In the Source box, type the entries that you want to appear in your drop-down list, separated by commas.
For example: Red, Green, Blue