A relative event is an event that is based on another event. For example, if you want your Twinkle to start flashing 5 minutes before bed time, you could use a relative event. The advantage is that if you later adjust bed time, the light still starts flashing 5 minutes before the new bed time. You add a relative event just like any other, except in the When dropdown, you select the amount of time before or after another event you want this event to occur.