Ghosts, also called Spirits, are souls of deceased humans that did not go with their reaper to Heaven or Hell and are stuck on Earth. The word Ghost is a common term for a soul that did not move on to an afterlife after they perished. They typically reside in The Veil, but they can occasionally appear in the physical plane. Descriptions of the apparition of ghosts vary widely: the mode of manifestation can range from an invisible presence to translucent or wispy shapes, to realistic, life-like visions. (Source: Fandom Wiki)
A ghost isn’t automatically good or evil. It’s behavior is defined by who they were in their life, what happened to them and how long they have resided in the Veil. Vengeful spirits are ghosts that are trapped by trauma or an unfinished business, and because of that can become violent and dangerous fast. A ghost can start off being utterly unaware that they have passed at all, but the longer any spirit has spent in the Veil, the more their behavior becomes erratic and harmful, and they begin losing touch with who they were in life.
Typical signs of ghost activity are cold spots, flickering electricity, moving objects and electro magnetic activity (EMF). On more rare occasions ectoplasm can be found. Ghosts have varying capabilities, but most can move object, physically hurt and teleport. Spirits are sometimes able to possess a human, but this isn’t very common.
Ghosts can be fought off using salt and iron, and in some cases hoodoo and spells. Spirits are tied to either their mortal remains or objects. Destroying whatever the spirit has tied itself to will also destroy the spirit. Bones have to be salted and burned, and the object can be either burned or otherwise destroyed.
It’s also possible to bring a spirit to rest without violent means if they’re willing, by having a pries perform last rites or by resolving the ghost’s issues.