How do you use the fill down tool?

The fill down tool is used in spreadsheet applications like Microsoft Excel or google Sheets to quickly copy the contents of a cell into adjacent cells below it. To use it, select the cell with the data you want to replicate, then click and drag the small square at the bottom-right corner of the cell (the fill handle) down to the desired range. Alternatively, you can select the cell, press "Ctrl + D" (or "Command + D" on Mac), and it will fill the selected cells below with the content from the top cell. This tool is helpful for populating columns with repeated values or extending formulas.