Established onExcel 365: threaded comments need vendor storageExcel 2016 and later: notes travel with the fileGoogle Sheets, web: both kinds, threads resolve the same way
The reason a number is what it is usually exists somewhere, and that somewhere is usually a comment thread or an email. Neither is part of the file's documentation, and one of them disappears on purpose.
Two kinds, in both products
A note is the older kind: text attached to a cell, shown on hover, travelling with the file wherever it goes. A comment in the modern sense is a thread with replies and a resolve action, and in Excel it requires the file to be on the vendor's storage to exist at all.
That requirement matters: a workbook moved off the service, or saved in an older format, loses the threads.
What resolving does
Hides the thread. The discussion that established why an assumption is 1.2, who agreed it and when, is now behind a menu item that says show resolved.
Resolving is an ordinary act performed for tidiness, and it is the act of filing the reasoning where nobody will look. The number remains, its explanation does not.
What else removes them
Pasting values over a cell removes its comments. Deleting a row removes the comments on it. Exporting to any other format removes all of them. Printing omits them unless a setting is changed. And copying a range to a new workbook carries some kinds and not others depending on the paste used.
So a comment is attached to a cell in a way that survives nothing that happens to that cell.
The mention, and where the record goes
Both products let a comment mention a person, which sends them a notification and in some configurations creates a task assigned to them. The thread becomes a small workflow.
The record of that workflow lives in the notification system and the task list rather than in the workbook, so the file and the discussion about the file are now in two places with no link between them beyond the cell reference, which may move.
What comments are good for
A question in flight. A remark about one cell that the next person to touch it should see. A proposal, which the entry on simultaneous editing recommends in place of editing.
All three are transient by nature, which is what comments are built for and the reason they behave the way they do.
The rule that follows
When a thread reaches a decision, write the decision onto the documentation sheet before resolving it. Date, decision, reason, who.
That converts a transient discussion into a durable record, and it takes one line. Nobody does it, and the entire cost of not doing it is paid eighteen months later by somebody asking why a number is what it is.
The comment that should have been a column
Where the same kind of remark appears on many cells — a reason code, an exception, a follow-up — it is data and belongs in a column, by the argument in the entry on formatting. Comments used as a column are uncountable, unexportable and invisible.
Before circulating a file
Look at the resolved threads as well as the open ones. They frequently contain internal discussion that was never meant to leave the organisation, they are not visible by default, and the inspector described in the previous entry removes comments as a category rather than selectively.
What we cannot verify
The two kinds of annotation, the storage requirement for threads, the resolve behaviour and the loss on paste and export are documented by the vendors and were confirmed on current builds. Whether a mention creates a task depends on the organisation's configuration of the surrounding services and was not tested across configurations.
Printing them
Both products can print notes, either where they appear or collected at the end, through a setting in the page setup that almost nobody has opened.
It is worth knowing for the one case where it matters, which is producing a paper record of a file for an audit or a submission, where the annotations are part of what is being recorded.
Where the discussion actually lives
For most workbooks it is in electronic mail, which is outside the file, outside the version history and outside anybody's search when the question comes up.
Nothing on this site fixes that. The only thing that helps is the habit in this entry: when a message settles something, one line on the documentation sheet.
What to do with an inherited thread
Read the resolved ones first. They contain the decisions, and the open ones contain the questions nobody answered, which is the less useful half for somebody trying to understand a file.
In short
- A note travels with the file; a thread in Excel needs the vendor's storage to exist.
- Resolving hides the discussion, so the number remains and its explanation does not.
- Pasting values, deleting rows and exporting all remove comments entirely.
- A mention turns the thread into a workflow whose record lives outside the file.
- Write the decision onto the documentation sheet before resolving the thread.
- A remark repeated across many cells is data and belongs in a column.