Validate and Save Step Data

What is the purpose of turning on the “Validate and Save Step Data” option for a button? What happens if it is not turned on?

It will validate the data you’ve entered into fields on the current step when the button is clicked and then save it. If you don’t turn it on, the data on the current step will not be saved, so you can’t access it in feathery and your users won’t be able to track it in subsequent sessions