Entities are what many people would consider angels or demons. They are completely spiritual or etheral in nature and actually have never lived as human beings. One major characteristic that may clue you into the fact that you are dealing with an entity is an overwhelming sense of good or evil associated with the apparition. There are two major types of entities:
1) Angelic entities serve mainly as messengers or protectors. Generally, when an angelic entity is encountered, it is a very private matter between the entity and the individual, or individuals that were meant to witness it. Other people in the room or area may not actaully see the angelic entity, but may feel a very strong sense of peace and well-being. Apparitions of Jesus Chirst and the Virgin Mary would be included in this category. Encounters with angelic entities are most common during a near-death experience, or at times of extreme stress.
2) Demonic entities are not very common. Demons are usually encountered only after an invidual or individuals invite one into their lives in one fashion or another. The most common way is for people to play with very forms of divinination, usually the Ouija Board. Another way a demonic entity can be invited into someones life or home is through automatic writing. The demon generally appears in the disguise of a sympathetic spirit who just wants to help you.