Archiving is how you keep your lists clean by removing items you're done with.
To archive an item
In Catch Up: Swipe the card to the left.
In your To-Do list: Swipe the item from right to left, then tap the Archive button.
To un-archive an item
If you archived something by mistake, you can easily get it back.
Go to the To-Do screen.
Tap the filter icon at the top right.
Toggle on Show archived. Your list will now include all archived items.
Find the item you want to restore, tap on it, and use the action menu to Un-archive it.