Microsoft Excel's Data Validation tool lets you add a drop-down list to a cell based on existing data in a column. However, how this works depends on whether the source data is part of a formatted ...

Cascading drop-down lists—where choosing a category like "Fruit" narrows the next list to "Apple" or "Pear"—are a staple of high-level data entry in Excel. The old INDIRECT method works, but it's ...