Buddhism talked about the various realms of existence; I believe these are states of being. Here, I share Master Hsuan Hua’s words about Hungry Ghosts. http://www.cttbusa.org/dharmatalks/10drealms10.htm The Ten Dharma Realms are not Beyond a Single Thought The Dharma Realm of Hungry Ghosts The ghostly crew delights in hate, Deluded by effects, confused about cause; Their ignorance and upside-downness Grow greater each day, deeper each month. Almost everyone has heard of ghosts, but not everyone believes in them. There are even Buddhist disciples who don't believe there are ghosts. Ghosts are masses of yin energy that have shadow and no form, or form and no shadow. Perhaps you have seen a dark shadow, but when you looked closer it disappeared. Or perhaps you've seen what seemed like a person, but which vanished in the blink of an eye. Such phenomena are difficult to understand. Among the Ten Dharma Realms, we are now discussing the Dharma Realm of ghosts. There are as many different kinds of ghosts as there are grains of sand in the Ganges River. There are infinitely many kinds of ghosts. Some are affluent and powerful ghosts that reign as kings over the ghosts' realm. Some ghosts are poverty-stricken and devoid of authority—it is often the poor ghosts who bother people and go about causing trouble. If you want to know how many kinds of ghosts there are, work hard at cultivation, open the five eyes and six spiritual penetrations, and then you'll know. As to people who say there are no ghosts, I tell them that if there are no ghosts, then there are also no Buddhas, people, or animals, because animals are transformed from ghosts, as are people, asuras, and so forth, even to gods, Arhats, Pratyekabuddhas, Bodhisattvas, and Buddhas. All realms come from the realm of ghosts, because the Ten Dharma Realms are not apart from a single thought of the mind, and one thought of the mind creates the Ten Dharma Realms. By conducting yourself as if you were a ghost, you fall into the ghosts' realm. Acting as a person does, you come to the human realm. Behaving like an asura, you join the ranks of asuras. Assuming the practice of an Arhat, you enter the realm of Arhats. Behaving like One Enlightened to Conditions, you enter that realm. Doing the deeds of a Bodhisattva, you join the retinue of Bodhisattvas. Performing the work of a Buddha, you realize Buddhahood. If you commit hellish offenses, you fall into the hells. All of this is brought about by the one thought that is right now in your mind. Thus we say that the Ten Dharma Realms are not beyond a single thought. The ghostly crew delights in hate. Ghosts enjoy exploding in a fiery rage when people are not good to them, and even when treated well they still get angry. They like nothing better than giving people trouble. They give you trouble whether you are good to them or not. There is an old saying: "Lighting a stick of incense calls forth ghosts." People light incense to pay respect to ghosts. Before you've paid respect to them they don't bother you, but once you make their acquaintance, the ghosts become a nuisance, make you sick, or give you some other trouble. Confucius said, "Respect the ghosts and spirits, but keep them at a distance." It is wise to pay respect to the ghosts and spirits, but otherwise keep your distance and don't get too close to them. Deluded by effects, confused about cause. They are unclear about results and don't understand their causes. As a result, they can't tell good from bad. Basically if you plant a good cause, you reap a good fruit; if you plant a bad cause you reap a bad effect. If you plant melons you get melons; plant beans and you'll get beans. Ghosts don't understand that. They plant eggplant and anticipate eating hot peppers, or plant hot peppers and think they will harvest cucumbers. Since they have no comprehension of principles, they act recklessly and in confusion. Their ignorance and upside-downness / Grow greater each day, deeper each month. They accumulate a lot karma every day. Their ignorance and upside-downness become deeper with each passing month. The more karma they create, the deeper their ignorance gets, and the deeper it gets, the more offenses they commit.