From Akashic Records
Ghosts are the supposed spirits of the dead, left over after death. Ghosts came in different forms, the most basic being intelligent hauntings and residual hauntings.
An intelligent haunting is a haunting where a conscious spirit is left behind. These are poltergeists, "generic" ghosts, etc.
A residual haunting is the idea that a strong emotion has left an imprint of some sort in an area, which can result in people seeing images and/or hearing sounds from that time. These work sort of like a broken record player, repeating at certain times and always happening the same way.
There is a popular belief that ghosts can be caught on photographic film and on digital photographs.
Orbs are said to be ghosts or spirits in spherical form that frequently appear in photographs. However, the fact that small particles of dust or water vapour give a very similar or even the same appearence as orbs, the belief in orbs as spirits is generally not very widespread and critizised.