Keeps the moths away. LOL
So Cedar is naturally resistant to rot from exposure to weather and has been used for exterior building for many years.
Cedar is very pretty to look at with regards to color and grain pattern. To get the most life out of your cedar siding using a sealant will help a great deal.
In very wet environments I usually recommend cement board siding as it doesn’t require maintenance and can stand up to horrible weather for a very long time.