The 6 realms of Buddhism are descriptions of heaven and hell which serve as metaphors to help us understand our own state of mind. When we are overwhelmed by identification with anger, for example, we may recognize we are in a hell realm. When we have everything we need yet are still plagued by jealousy, we may recognize we are in the realm of the demi-gods. The language of the 6 realms can help us understand how our state of mind has the power (for good or bad) to trigger rebirth in a completely different world.