Cell specific guidance notes (similar to comments but different)

[fhphillips]

I'm looking at a spreadsheet where these notes appear just below the cell when the cell is selected. They don't appear to be comments and seem neater / more functional as they only appear when the relevant cell is selected but they don't disappear when the cursor is moved. Please can anyone help me with how to insert these into my own spreadsheets?

[#2]

https://support.microsoft.com/en-us/office/apply-data-validation-to-cells-29fecbcc-d1b9-42c1-9d76-ef...

Select the Show input message when cell is selected checkbox to display the message when the user selects or hovers over the selected cell(s).