Humans have been able to conquer and find answers to most of the mysteries of the world, but death remains unconquered. Although there have been many theories told about life after death, nothing has been clearly evident. The speculations over ghosts have been raving for a long time, but concrete evidence has not been found. According to believers, there are different types of ghosts, such as traditional apparitions, crisis apparitions, doppelgangers, and anniversary ghosts.

Traditional apparitions are ghosts that interact with human beings. This can be for good or for bad. These ghosts are said to hide objects, frighten people, throw objects or plea for help. These ghosts are said to be present because of unfinished work. This can be due to their death in untoward circumstances, and they generally seek human help to resolve the issue and progress into a different realm. These spirits are said to be "intelligent" yet haunting, as they appear to be aware of the people around them and their surroundings.

Crisis apparitions are ghosts who appear to inform someone about danger. They are solid or transparent by nature. Anniversary ghosts appear on the anniversary of their death caused by some tragic event. These ghosts are commonly found in haunted houses or castles, and often relate to legends of tragedies from centuries past.

Messenger ghosts, like banshees, appear to family members to herald the death of another family member. Poltergeists are noisy spirits who produce sounds like ""psychic explosions"" from a teenage boy or girl.

Speculations are believed to be the soul or spirit of humans who have passed on from this life. These are orb-shaped and have been seen by many. Some say these spirits have a separate life form and are undetectable to the human eye because of their finer tissue.

Although there has been a lot written about ghosts, nothing can be termed as reality. Scientists still believe that ghosts and spirit is something that has been born out of the fear of human.