An Anchor is what keeps a ghost bound to the mortal realms instead of moving on. Every ghost has at least one anchor rooting it to the physical world. Some powerful spirits may have more. The number and nature of a ghost's anchors depends on the individual and the circumstances surrounding its death. In most cases, an anchor is a physical place, object or even a person that held great emotional significance to the ghost during its mortal existence.
Ghosts must remain close to their anchors at all times, whether they manifest or not. If the Anchor is destroyed, the Ghost goes on into the afterlife.