Ghosts have been a popular subject for millennia, appearing in countless stories, from "Macbeth" to the Bible, and even spawning their own folklore genre: ghost stories. Ghosts are perhaps the most common paranormal belief in the world. Part of the reason is that belief in ghosts is part of a larger web of related paranormal beliefs, including near-death experience, life after death, and spirit communication.
The idea that the dead remain with us in spirit is an ancient one, and one that offers many people comfort; who doesn't want to believe that our beloved but deceased family members aren't looking out for us, or with us in our times of need? Most people believe in ghosts because of personal experience; they have seen or sensed some unexplained presence.
The science and logic of ghosts
Personal experience is one thing, but scientific evidence is another matter. Part of the difficulty in investigating ghosts is that there is not one universally agreed-upon definition of what a ghost is. Some believe that they are spirits of the dead who for whatever reason get "lost" on their way to The Other Side; others claim that ghosts are instead telepathic entities projected into the world from our minds.
Ghost hunters use many creative (and dubious) methods to detect the spirits' presences, often including psychics.
The evidence for ghosts is no better today than it was a year ago, a decade ago, or a century ago. There are two possible reasons for the failure of ghost hunters to find good evidence. The first is that ghosts don't exist, and that reports of ghosts can be explained by psychology, misperceptions, mistakes and hoaxes. The second option is that ghosts do exist, but that ghost hunters are simply incompetent. Ultimately, ghost hunting is not about the evidence (if it was, the search would have been abandoned long ago). Instead, it's about having fun with friends, telling stories, and the enjoyment of pretending they are searching the edge of the unknown. After all, everyone loves a good ghost story.