Pretas are invisible to the human eye, but some believe they can be discerned by humans in certain mental states. They are described as human-like, but with sunken, mummified skin, narrow limbs, enormously distended bellies and long, thin necks. This appearance is a metaphor for their mental situation: they have enormous appetites, signified by their gigantic bellies, but a very limited ability to satisfy those appetites, symbolized by their slender necks.
Pretas are often depicted in Japanese art (particularly that from the Heian period) as emaciated human beings with bulging stomachs and inhumanly small mouths and throats. They are frequently shown licking up spilled water in temples or accompanied by demons representing their personal agony. Otherwise they may be shown as balls of smoke or fire.
Pretas dwell in the waste and desert places of the earth, and vary in situation according to their past karma. Some of them can eat a little, but find it very difficult to find food or drink. Others can find food and drink, but find it very difficult to swallow. Others find that the food they eat seems to burst into flames as they swallow it. Others see something edible or drinkable and desire it but it withers or dries up before their eyes. As a result, they are always hungry.
In addition to hunger, pretas suffer from immoderate heat and cold; they find that even the moon scorches them in the summer, while the sun freezes them in the winter.
The sufferings of the pretas often resemble those of the dwellers in hell, and the two types of being are easily confused. The simplest distinction is that beings in hell are confined to their subterranean world, while pretas are free to move about.
Pretas are generally seen as little more than nuisances to mortals unless their longing is directed toward something vital, such as blood. However, in some traditions, pretas try to prevent others from satisfying their own desires by means of magic, illusions, or disguises. They can also turn invisible or change their faces to frighten mortals.
Generally, however, pretas are seen as beings to be pitied. Thus, in some Buddhist monasteries, monks leave offerings of food, money, or flowers to them before meals.
