A comment in spreadsheet software like Microsoft Excel is indicated by a red triangle in the upper-right corner of a cell, which shows the comment when hovered over or selected.
In Microsoft Excel and similar spreadsheet software, the presence of a red triangle in the upper-right corner of a cell indicates that a cell has a comment attached to it. When you hover over the cell or select it, the comment appears as a small pop-up box containing text, which can provide additional information or notes related to the cell's content. This feature is often used for collaboration and to provide clarification without altering the cell's displayed data.