This Scribe shows you how to visibly mark duplicates in a single column in Google Sheets using conditional formatting. The same logic came be applied to multiple columns i.e. entire datasets

Select the second cell in the column where you want to mark duplicates. If your column does not have a column header, select the first cell

Highlight the entire column of data: For PCs, press [[ctrl]] + [[shift]] + [[down]]. For Macs, press [[cmd]] + [[shift]] + [[down]]

Click "Format" and then "Conditional formatting"

How to mark duplicates in Google Sheets

Tiffany made this Scribe in 19 seconds.