[Note: We've recently retired this feature in favour of our new 'small text' option]
Adding a description to your notes is great for when you've collected a lot of information and you want to keep track of where it came from.
To add a description:
Select a text, image or link card
Click "Power-ups"
Click "Add a description"
Tip: you can use CMD-Enter to instantly create another text card under the one you're currently editing. Doing this will copy across the descriptions of the card you're editing. This helps when you have a lot of data to input form the same source.