The word Poltergeist is a German word which translates as restless spirit. Poltergeist hauntings usual involve objects flying violently across the room or being found moved, damaged or manipulated without anyone having touched it. This may be accompanied with mysterious loud noises, bangs or eerie sounds emanating from walls and ceilings. In many documented cases, the focus seems to be on a person or persons rather than a place and the most common association is with young or teenage girls. There is a crossover with possession - usually when the 'spirit' has evil intent and seemingly takes over the identity of the person - but differs in that the action is taking place near or around the girl rather than being caused directly by her.
One of the most famous cases was that of the Enfield Poltergeist, which took place in a modest house in the London suburb in 1977. Two sisters, Margaret (13) and Janet (11), who lived with their mother Peggy, reported to her that they heard noises coming from the walls. Peggy called the police and added in her report that she had seen a chair move on its own. The PC said that she saw a chair "wobble and slide" but “could not determine the cause of the movement”. Over the next 18 months, more than 30 people, including neighbours, psychic researchers and journalists, said they variously saw heavy furniture moving of its own accord, objects being thrown across a room and the daughters seeming to levitate several feet off the ground - there is a famous photograph of one of the girls levitating whilst her terrified siblings cower under the bedclothes. The activity in the house attracted considerable press attention and the story was covered in British newspapers such as the Daily Mail and Daily Mirror until reports came to an end in 1979.
It is telling that so often reports of poltergeists focus on children. The most likely explanation is that some children are sometimes just natural pranksters and too often adults see what they want to see. Whenever controlled tests or investigations take place, the objects no longer move, noises are often traced to prosaic explanations and when the protagonists are monitored with cameras and recording equipment the poltergeist seems to give up and go away. In the Enfield case, a video camera in the room next door caught Janet bending spoons (Uri Geller was famously on TV quite a lot at that time), probably to then blame it on the ghost. The girls later admitted to faking 'some' percentage of it, but as skeptical investigator Joe Nickell said:"the evidence suggests that this figure is closer to 100 percent". As for the levitating picture? It's a still photograph, she could just as easily be jumping.