The Wheel of Life (bhavacakra), particularly significant in Tibetan Buddhism, is a painting of a wheel divided into six sections representing realms of rebirth in which a wide array of beings dwell.

The earliest depiction of the Wheel of Life is a fresco from the sixth century CE of Ajaṇṭā. According to the Divyāvadāna, a collection of moral stories about good and evil deeds, Buddhism’s founder, Buddha, established and approved the use of the Wheel of Life to provide instruction for the non-literate about Buddhist truths. 

The Wheel of Life artistically depicts saṃsāra, which is the endless process of birth, death, and rebirth out of which the Buddhist aims to escape by attaining liberation (nirvana) through a faithful interpretation of Buddha’s teachings. All six realms are possible realms of rebirth and where one is reborn will be determined by his or her karma.

The six realms surround a central hub containing a cock (desire), pig (ignorance), and snake (hatred) who are chasing one another. These animals are symbols of the Three Poisons of desire, ignorance, and hatred. The wheel is also grasped by Yama, the god of death, who symbolizes the all-pervasive nature of death and impermanence.

The six realms are:

1. Hell – This is the lowest of the realms where its inhabitants suffer the consequences of evil acts done in their previous lives. This can include being boiled in oil or hacked limb from limb. Hells are not, however, a final place as one might think of hell in the Judeo-Christian tradition.
   
2. Animal – The animal realm is above hell. It is far from ideal because animals are governed by brute instinct and lack the intellectual capacity to understand their situation, thus jeopardizing an attempt to attain liberation.
   
3. Ghost – Above the animal realm is the realm of ghosts. These are believed to be unhappy spirits, most of whom were once humans, who exist on the fringe of the human world. In the human world, it is possible to glimpse ghosts as shadowy forms. Artistically, they are depicted as wraith-like creatures with small mouths and big bellies, and who are consumed by desire that can never be satisfied. 
   
4. Titan – this realm was added to the world system in later sources. It is one consisting of competitive demonic war-like beings with violent impulses who lust for power that can never be satisfied.
   
5. Human – It is both difficult and desirable to be reborn as a human. Humans have reason and free will they can use to understand the Dharma (the Buddha’s teachings) and therefore implement it effectively for attaining nirvana. The human realm strikes a balance between suffering and pleasure.
   
6. Gods – The realm of the gods is the highest on the Wheel of Life. Although it is depicted at the top, the realm is still imperfect. Because the gods have rich and happy lives, they fail to recognize the truth of suffering, which can undermine motivation to seek liberation from the Wheel of Life. At some point, they will experience rebirth in another, less desirable realm.