What's in a cell? The fact is that often you cannot tell what is in a cell in a spreadsheet just by looking at it.
Consider the following:
When you see a blank cell, is it meant to be an empty cell or zero?
When you see a number in a cell, are you actually looking at a number, or does the cell contain a formula or text?
When you see a value in a cell what are you looking at - data input, data output, or an intermediate calculation.
Your spreadsheet should be easy for the user to understand. All the information the user needs to know what your spreadsheet is doing should be on the spreadsheet itself.
If the purpose of the cell contents is not immediately clear to the user, then think about using cell comments. Cell comments are an excellent way to provide information without cluttering up the worksheet. They are best used if the information does not always have to be visible. You can see how I applied this technique for a client in the video below. If you do not want to watch the entire video, skip to 3:30 for a demo of how I used comments for clarification.
Skip to 3:30 to see how to use Comments for instructions or clarification.