Paranormal Activityis a 2007 American supernatural horror film written and directed by Oren Peli .The film centers on a young couple, Katie and Micah, who are haunted by a supernatural presence in their home. It is presented in the style of " found footage ," from a camera set up by the couple in an attempt to photograph what is haunting them.

Originally developed as an independent feature , the film was acquired by Paramount Pictures . It received a limited U.S. release on September 25, 2009 and nationwide release on October 16, 2009. The film earned nearly $108 million at the U.S. box office and $194 million worldwide.Paramount/DreamWorks acquired the U.S. rights for $350,000.It is the most profitable film ever made, based on return on investment ,although such figures are difficult to verify independentlyas this is likely to exclude marketing costs.

A prequel,Paranormal Activity 2, was released on October 22, 2010, and was followed by a third film titledParanormal Activity 3on October 21, 2011.

In 2006, Katie (played by Katie Featherston ) and her boyfriend, Micah (Micah Sloat), are a young couple who recently moved into a two-story tract house in suburban San Diego, California . Katie claims that an "Evil" presence has haunted her since childhood and believes that it has followed her to their new home. Each night, Micah mounts a video camera on a tripod in their bedroom to record any paranormal activity that might occur while they sleep, in the hopes of solving the problem himself. The first night, the only thing they catch are footstep noises. Katie hires a psychic, Dr. Fredrichs (Mark Fredrichs), who assesses that she is being haunted not by a ghost, but by a demon . He says the demon feeds off negative energy, and its intent is to haunt and torment Katie no matter where she goes. He advises them not to taunt or communicate with the demon, and to contact demonologist Dr. Johann Averies for help. Though Katie seems interested and engaged in the situation, Micah does not take it seriously.

The camera captures several supernatural phenomena which remain minor at first, such as the bedroom door moving by itself during night 3. During night 5 however, Katie wakes up from a nightmare and it is revealed that something was whispering to her in her sleep. Micah begins to taunt the demon and the phenomena worsens; during night 13, they are awoken by an otherworldly screech and a loud thud. They go downstairs to investigate and find the chandelier moving by itself. On night 15, Katie awakens and spends several hours standing by the bed staring at Micah while he sleeps, before going outside to sit on the backyard swing. Micah awakens and tries to convince her to come inside but she refuses, her voice dreamlike and detached. When Micah goes inside to get her a blanket, he finds the TV turned on in the bedroom, and is then startled by Katie, who followed him inside but says that he woke her up. Katie remembers nothing the next day.

Katie, already irritated by Micah's flippant response to the situation, becomes irate when Micah brings home a Ouija board despite Dr. Fredrichs' warnings. The two go out of the house that evening, leaving the Ouija board in the living room. The curtains and plants start to blow around and the Ouija board's planchette moves on its own. A small fire erupts on the board, but it extinguishes itself before they get home. It seems that the board has left them an unrecognizable and unreadable message. On night 17, Micah sprinkles talcum powder in the hallway and when the couple is awoken by noises, they find non-human footprints leading to the bedroom from the attic. In the attic, Micah finds a burnt photograph of a young Katie, which was previously thought to have been destroyed in an unexplained house fire.

The next night, a light turns on and off and the bedroom door slams shut. Loud banging is heard, as something is apparently trying to get in. They discover that the glass over a photo of them has been smashed, with Micah's image scratched. Dr. Averies is abroad when Micah finally agrees to invite him, so Dr. Fredrichs comes instead. Upon his arrival, Dr. Fredrichs immediately has a sense of dread. He apologetically leaves despite their pleas for his help, stating that his presence is only making the demon angry. On night 19, a shadow moves across the bedroom door. The paranormal activity starts to become physical; Katie is pulled out of the bedroom by an invisible force during night 20. Stressed and exhausted, the couple decide to go to a hotel. Micah finds Katie gripping a cross so tightly that it bloodies her palm. Micah, angry at a situation he cannot control, burns the cross and the picture found in the attic. Just as he is set to leave, a suddenly apathetic, languid Katie insists that they will be okay now, her voice flat.

On night 21, Katie awakens to once again stand and stare at Micah while he sleeps. She walks out of the darkness, holding a large bloody kitchen knife, her shirt bloodied. She sits beside the bed, holding the knife and rocking herself, until about 2 p.m. the next day, when her friend Amber calls and leaves a message expressing her concern. At about 9:20 p.m. that night, Katie is still sitting and rocking by the bed, and Amber can be heard entering the house. During this short period, Katie stops rocking and after Amber sees Micah's body, she runs out of the house and Katie resumes rocking. Half an hour later, just after 9:50 p.m., police enter the home and discover Micah's body as well. As they are checking Micah for vital signs, a light turns on in the bedroom down the hallway, but before the police see it, the light turns off again. They discover Katie, still sitting beside the bed with the knife. As they call to her, she wakes from her catatonic state and seems confused. As she approaches them, knife in hand, calling Micah, they ask her to drop the weapon. Suddenly the bedroom door behind the police officers slams shut, startling them and causing them to shoot Katie, who collapses on the floor. The police then call dispatch and check the bedroom at the end of the hall, but find nothing. They discover the video camera, still running. A dedication to and a picture of Katie and Micah are then shown.

Alternate endings

Once Paramount acquired the film, two alternate endings were developed for it, with one of them eventually being used in the theatrical version. The original ending for the film was available for a time for viewing on the Internet before Paramount exerted a claim of copyright on the material.

In one of them, seen in the theatrical and blu-ray versions of the film, after Katie comes out of bed, she stands beside it staring at Micah for approximately two hours and then walks downstairs. After a moment of silence, Katie screams Micah's name, waking Micah who rushes to her. The camera records Katie screaming incessantly, while Micah tries to talk to her when he suddenly lets out a cry of pain. Katie's screaming stops and a brief silence is followed by the sound of heavy footsteps coming up the stairs. After another brief silence, Micah's body is violently hurled at the camera, knocking it over sideways and revealing Katie standing in the doorway. She then slowly walks into the room, her clothing soaked with blood. Crouching over his body, she sniffs Micah (who has evidently been murdered) and then slowly looks up at the camera with a sly smile. As she lunges toward the camera, her face takes on a demonic appearance just as the scene cuts to black. An epilogue text states that Micah's body was discovered by the police on October 11, 2006, and that Katie's whereabouts remain unknown.

The second alternate ending was shown at only one public viewing and was later offered as an alternate ending on the DVD and Blu-ray releases of the film.In this ending, Katie gets out of bed and stands staring at Micah, as she did in the theatrical ending, except she does not move to Micah's side of the bed. About three hours pass, then she finally goes downstairs. She lets out a blood-curdling scream, which wakes Micah up and he runs downstairs. The screaming continues, and the sounds of a struggle are heard before the noises abruptly stop. There is silence for a short while before loud footsteps are heard on the stairs. Katie then walks into the bedroom, Micah's blood covering her shirt, with a knife in her hand. She closes and locks the bedroom door, then walks up to the camera, standing idle briefly. She then takes the knife and slits her own throat, then falls to the floor, dead.