Reincarnation is the belief that your soul gets to live numerous lives. When you die, your soul simply enters a new soul. Some believe there is a purpose to this reincarnation, and that is to find enlightenment. Others believe that it’s simply a cycle, forever unbroken. They often believe that you can occupy different types of vessels. You could have been a cat or a moose or a redwood or a butterfly in a previous life.
What animal you get to be in your next life is determined by your behavior in this life.