In Excel, you can use data validation to create drop down lists on a worksheet. Usually, a simple list is all that’s needed, to make it easier for people to enter the correct data.
In this example, we use dependent drop down lists, where the cities shown in the second list depend on what country is selected from the first list.
In this video, you can see how to set up the lists for the data validation, and use the INDIRECT function to show the correct city list, depending on the selected country.
If you prefer written instructions for this technique, you’ll find another example of this technique on the Contextures website, on the Dependent Data Validation page.