A ghost is an apparition that appears in the physical world but cannot be physically seen. They are often associated with a specific place, such as the site of a violent or sudden death. Ghosts are often viewed as beings with unfinished business, which can include revenge or seeking justice.
A well-developed ghost is a cornerstone of your story, and can add a whole lot of depth to your work. They should be treated like any other character in your story and be given a backstory, personality, and motivations. This will help your ghost seem more realistic and believable, especially when the hero/heroine interacts with them.
The ghost is a classic supernatural character that can be found in almost any genre of fiction. From the haunting of an old house to the spectral armies of world wars, ghost stories have been told for thousands of years. They are popular because we have an innate curiosity about the unknown and a fear of death.
Whether it is to scare or entertain, a good ghost story should cause the reader to feel physical reactions like goosebumps and hairs standing on end. The key to this is strong, simple descriptions. Many amateur writers lean towards using complex words to show off their knowledge of high-school English, but overly descriptive language can be confusing and hard for the brain to process. Keep it simple and easy to understand, as this will have a greater impact on your readers.