The six worldly realms are collectively termed samsara, or cyclical existence. They are depicted in Buddhist iconography in the image known as the Wheel of Life.
Samsara has three lower realms and three higher realms.
The three lower realms are the worlds of great sufferings:
1. In the hell realms, beings suffer from the never-ceasing heat of burning flames and molten metal or the cold of freezing snow and ice.
2. In the hungry ghost realm, beings suffer from ever-tormenting hunger and thirst.
3. In the animal realm, beings suffer from fear, dullness, and servitude.
The three higher realms are worlds of many kinds of happiness, yet they also involve endless suffering.
4. In the realm of the demigods, beings enjoy material prosperity, but they suffer from their constant warring and fighting.
5. In the realm of the gods, beings enjoy great happiness and prosperity, but these enjoyments are merely ever-changing sensual pleasures, and they also suffer. They live long lives compared with human life spans, but because of their lack of awareness, they feel as if it has all ended in a short time. The god realm is part of our mortal mundane world, not a paradise or kingdom like that of the gods of Western mythology. As soon as their karma in the god realm is exhausted, these beings will suffer by dying and being reborn in lower realms, where they are subject to their karmic consequences.
6. In our human realm, even if we are fortunate to enjoy great intellectual abilities, material abundance, and positive experiences, we nonetheless suffer from the chain of birth, sickness, old age, and death. We suffer by losing what we want, being forced to accept what we don’t want, not getting what we desire, and having to protect what we have.
Source: Taken from the following book — Thondup, Tulku. Peaceful Death, Joyful Rebirth: A Tibetan Buddhist Guidebook. Boston, MA: Shambhala Publications, 2005.
In our human realm, even if we are fortunate to enjoy great intellectual abilities, material abundance, and positive experiences, we nonetheless suffer from the chain of birth, sickness, old age, and death.
We suffer by losing what we want, being forced to accept what we don’t want, not getting what we desire, and having to protect what we have.
(Tulku Thondup, Peaceful Death, Joyful Rebirth)