Six Realms of Existence

The 'six realms of existence' or the 'six paths of rebirth', are the six main types of birth that beings may have within Buddhist cosmology.

Which state we are born into is driven by our karma - our actions and states of awareness from previous lives.

According to Buddhist teachings, we will endlessly incarnate within these realms until we receive and practice the teachings, and through them break free of the karma that pull us into the six realms, thereby attaining enlightenment.

The six realms are :

1) God Realm (Deva)
Defined by bliss and pleasurable states of all types, this realm is reminiscent of Greek myths about the realm of the gods.

But in Buddhism, this is not an immortal state, and also not the ideal one for attaining liberation. We can become addicted to pleasure here, including meditative bliss, and can become trapped, forgetting to work towards liberation, and falling into lower realms because of this forgetfulness and self-absorption.

2) Demi-God Realm (Asura) 
Also pleasurable, this realm is nevertheless defined by jealousy and competitiveness.

Although a birth here does offer more opportunities for pleasure than a human birth, here we are prone to coveting the pleasures of the Devas, which we can see (just as animals and humans can see each other) .

In this state, we are prone to envy and/or a sense of victimhood - that we are not getting our fair share - and become fixated on evening the score.

3) Human Realm 
A middle realm, our human existence is defined by our ability and free will to experience any state, from blissful to hellish.

It is therefore perfect for attaining enlightenment, because there is just enough suffering to motivate us to seek liberation (unlike in the god realms, where we are easily distracted by pleasure) but not so much that we cannot hear and practice the teachings (unlike in the lower realms, where we are so consumed by our suffering that we cannot practice).

From a human birth, we can cultivate the compassion and wisdom necessary to free ourselves from the entire wheel of samsara.

In this realm we also have the most control over our future births, because we can influence our karma through our choices, whereas in the other realms we generally do not move into another birth until the karma that has brought us there has run its course.

4) Animal Realm 
Within Buddhist cosmology, the animal realm is defined by ignorance, and an inability to think for oneself.

Life is one-dimensional and survival-oriented, with little free will or choice.

5) Hungry Ghost Realm (Preta)
This realm is defined by constant desire and greed.

In this realm, we are so overcome by our desire for more, more, more - whether food, drink, sex, wealth, or even certain emotional states - that we are consumed by it, and cannot focus on anything else.

It is analogous to the state of an addict, in which getting the next 'fix' trumps all other concerns.

In this state, we cannot practice the teachings because we cannot focus on anything other than our wants.

6) Hell Realm (Naraka) 
This realm is defined by hatred and rage, and by defining all other beings as enemies.

Within this realm, there is no opportunity for compassion or desire for the teachings to arise, as all our momentum goes toward fighting others, and suffering the consequences.

Depictions of this realm in various Buddhist schools is very similar to those found in other religions, with fiery torments.

But within Buddhist cosmology this state, like all the others, is not permanent. Instead, when the negative karma that brought us here has run out, we will be reborn into another realm, with the possibility of working towards a human birth again.