Ghosts are disembodied astral spirits. Some humans may witness them as apparitions.
An astral spirit is a term used in spiritualism and holism. During the Renaissance, it was used in a Platonic format to designate the "aetheric vehicle or starlike garment surrounding the soul which descended from heaven and entered the individual body".
Attached spirits may be a ghost that is attached to an object, human body or soul in some way. It is often thought that the spirit has some business in the world that has not been resolved yet, which is usually crime related. In some cases they can be considered possessions. Others view them as familiars.
Familiars or "animal guides", are supernatural entities that serve as guides or give aid in some way. They appear in numerous guises, often as an animal, but also at times as a human or humanoid figure. In some eyewitness accounts, they were described as "clearly defined, three-dimensional… forms, vivid with colour and animated with movement and sound", unlike the typical description of a ghost having an undefined form.
Spiritualists of the nineteenth century held the Platonic view that astral spirits were ghosts or vampires that would rise from the grave of the deceased in order to steal the blood and vitality of the living, while the physical body would remain in the grave. It was considered to be a remnant of the deceased in some form.
A poltergeist (German, meaning "knocking spirit") may be a ghost that has the ability to affect the physical world in some way. For example, by creating knock-knock sounds, or by moving objects.
Astral spirits were thought to be one of the three parts of the human soul that contained the "thoughts, cogitations, desires, or imaginations that were impressed upon the mind at the time of death", which would include lust and anger