Does the Hindu religion teach about the existence of ghosts and spirits?
Hinduism teaches that ghosts are people without physical bodies, the souls of people who died before their time, typically by tragedy. Many Hindus believe human beings have two bodies. When the physical life ends prematurely with the passing of the first body called the gross body, the person will remain in an ethereal state in the second body called the subtle body, until the remaining time of the life is complete and an entirely new body can be inhabited. Having not fully experienced life's joys, ghosts experience great suffering due to the senses remaining intact, but without a physical body to interact with our world through. Therefore, it is impossible to satisfy the ghost's desires and a hell-like state of existence is suffered for the set period of time allotted.
Within Hinduism, many followers prefer cremation of the deceased person's body, as this is believed to prevent the soul (or ghost) of the person from trying to re-enter their old body after death. This idea is believed to be especially true for ghosts who are materialistic in nature, or suffer from earthly lusts and addictions. Many Hindus believe that some ghosts will seek other people's bodies in attempts to fulfill those lusts and addictions. This is believed to be the root of some life problems, and is known as ghost possession, occuring when people weaken themselves through times of stress, making themselves subject to ghostly influence. This belief in ghost problems, ghost illness and ghost possession stems from ancient, sacred Hindu writings and idealogy, which teaches a somewhat complicated system of dharma, karma and re-birth. Hinduism has therefore created various rituals for followers to be rescued from ghosts and the problems they cause, and to also assist the ghosts onward in their life journey.
Hindu beliefs teach that we are surrounded by a multitude of spirit entities, which exist within the "ether" that encompasses everything. This ether, which could be equated to spirit, or energy is also called, akasha. The Akashic Records are believed to contain every event in time, somehow recorded in the ether as an imprint of energy that may be possible to be re-played or visibly seen by those with psychic abilities. Hinduism teaches that seeing into the akasha which contains the Akashic Records, in other words, seeing ghosts, is possible by those who know how to use the third eye. Interestingly, Hinduism also teaches that the soul of a person will continue to re-incarnate on earth until free from all physical, earthly desires, which ends the cycle of ghosts and suffering. See: Hungry Ghosts.
Buddhism and Hinduism have influenced each other, though they have fundamental differences. Buddhism does find its roots within Hinduism, as Buddha was born into a Hindu family, but later found enlightenment which spawned new, radical teachings upon which Buddhism was founded. Teachings concerning ghosts in Buddhism also exist.