Tips to onboard account

There are a gazillion posts about tipping, but i'm still not sure about the following. I'm going on the Magic, and i simply want to know if the tips are automatically added to the onboard account or not.

On DCL FAQ,s it says that they may be added to onboard account if not pre-paid, so i'm just not sure what it means.

I'm used to going on cruises (other lines) where they are automatically added, so the only thing we have to worry is giving little extras here and there when warranted.

thanks