Writing notes in cells helps communicate information to your team and serves as a reminder as to what changes were made and why. 

It's an easy way to indicate how you're breaking down a budget, explain why an invoice is being paid on an alternative date, or give a reason why you set a budget for a certain amount, etc.. 

To create a note, just click into any cell and click the Notes section (in the top right of the budget popover)

Then you'll see an area to write anything you'd like to make note of:

Cells with notes on them will also have a small triangle on the top right corner so you don't have to click into the modal to tell if a note exists:

When you scroll over the triangle, the note will appear:

 To remove a note simply delete the text from the 'Notes' section and hit save.