The film's concept derives from a recurring nightmare the director used to have, where he would be stalked by a predator that continually walked slowly towards him.

The theatre featured at the beginning of the film is the Redford Theatre, a historic Japanese style theatre with a fully functioning Wurlitzer organ, in the Old Redford neighborhood of Detroit, MI. The Evil Dead (1981) premiered there.

According to the production company the film's budget was $1.3 million and was shot entirely in the state of Michigan for tax advantages. A year after its theatrical release it grossed over $20 million.

The time frame of the movie is intentionally kept ambiguous so that it resembles a dream. Some of the cars shown are from more recent times. Many appear to be from the '60s to late '80s. Early CRT television sets are shown whenever the characters are watching movies. Conflicting technology include Yara on a device that looks like a shell compact, but she reads from it like an e-book reader and using it as a light source at one point. Also, the girl from the beginning of the film uses a cellphone and drives a modern automobile, with several modern vehicles in view.

The monstrous "It" is often said to be a metaphor for sexually transmitted diseases and sexual promiscuity. When asked about the film's concept, director David Robert Mitchell states, "The basic idea of being followed by something that looked like different people, that was very slow, and always coming came from a recurring nightmare I had when I was a kid. Later, as an adult, I added the sexual aspect of passing on this terrible thing. It came at two different points of my life."

The dilapidated house that Hugh hid out in, and that Jay and her friends explored, is a house style called the American Foursquare. This style was popular from the 1890s through the 1930s. Many floor plans for the foursquare feature "circular" traffic patters, where one can proceed through several rooms and return to the starting point without ever reversing the path: kitchen, vestibule, living room, dining room, and kitchen, for instance. In some homes, adjoining bedrooms shared closets and bathrooms. This kind of "fluid" floor plan would make this style of house particularly desirable if an escape from "It" was needed.

Jay and Kelly's mother's face is never clearly shown. In the first scene in which she appears in the film she is seen talking on the phone in the kitchen with her face completely covered by her hair. In every other scene her face is either out of focus or partially cut by the frame.

Following overwhelmingly positive first weekend reception from critics and audiences, the film's originally-planned VOD/theatrical release was cancelled in favor of a theatrical-only release.

The poem that Jay's English teacher reads out loud is T.S. Eliot's "The Love Song of J. Alfred Prufrock." The poem seems to share some commonalities with the film.

Shot mainly with wide-angle lenses to give the film a more expansive, intimidating feel.

David Robert Mitchell has cited the works of George A. Romero and John Carpenter as major influences on his style of filming and creative decisions on It Follows (2014).

Not only do the set props prevent the viewer from placing the year, the clothing prevents the viewer from placing the time of year. Throughout the film's short duration clothing ranges from coats, jackets, t-shirts and swimsuits during the day, to barely anything at all at night... all outdoors, with no signs of discomfort.

Jay is short for Jamie, a tribute to scream queen Jamie Lee Curtis. In the film, Jay has a sister named Kelly. Jamie Lee Curtis also has a sister named Kelly Curtis.

The director David Robert Mitchell said in an interview that the 'monster' could potentially board a plane in order to follow the cursed person.

Disasterpeace recorded the score for the film because the director, David Robert Mitchell, was a huge fan of the video-game Fez (which Disasterpeace did the music for).

The entire score by Disasterpeace ("Disasterpeace") was completed in less than three weeks.

The film takes inspiration from several horror films and their tropes from the '60s to the '80s, especially from the slasher classic Halloween (1978). The girl in the opening scene of the film is named Annie, and one of Laurie's friends in Halloween (1978) was named Annie Brackett.

The film alludes to teenage problems through its props. This is seen when Jay is lining up blades of grass on her upper leg (cutting/suicide), as well as Jay's uneaten tray of food in her room (eating disorders) that first has a pill laid out on a napkin, and later is the only thing touched from the tray (drug dependency).

In an interview with Vulture in which he was explaining the reasoning behind the group's seemingly vacuous plan to lure the creature leading up to and during the final confrontation, director David Robert Mitchell insinuated that they're just kids trying to find a way to defeat the threat in their own way. He explains, "It's the stupidest plan ever! [Laughs] It's a kid-movie plan, it's something that Scooby-Doo and the gang might think of, and that was sort of the point. What would you do if you were confronted by a monster and found yourself trapped within a nightmare? Ultimately, you have to resort to some way of fighting it that's accessible to you in the physical world, and that's not really going to cut it." He goes on to state, "We kind of avoid any kind of traditional setup for that sequence, because in more traditional horror films, there might be a clue that would lead them to figure out a way to destroy this monster. I intentionally avoided placing those. Instead, they do their best to accomplish something, and we witness its failure. It's a probably a very non-conventional way of approaching the third-act confrontation, but we thought it was a fun way to deal with it."

Yara reads out a section from Fyodor Dostoevsky's novel, "The Idiot", which sums up the "But here I should imagine the most terrible part of the whole punishment is, not the bodily pain at all-but the certain knowledge that in an hour,-then in ten minutes, then in half a minute, then now-this very instant-your soul must quit your body and that you will no longer be a man-and that this is certain, certain!"

One of the old movies the kids are watching on TV, which stars a young Peter Graves and has a character with large eyes, is Killers from Space (1954).

Due to the surprise success of the film, there have been talks of a possible sequel.

David Robert Mitchell started writing the screenplay in 2011.

The film initially recouped its minuscule budget five times over with $10 million worldwide. As of 2016, the gross ballooned to $20 million worldwide.

The first manifestation of "It" that Jay sees while she is tied in the wheelchair is Hugh/Jeff's mother.

A total of eleven actors has portrayed It or The Entity onscreen. In chronological order, the actors who show up in appearance as the creature are Ruby Harris, Ingrid Mortimer, Alexyss Spradlin, Mike Lanier, Olivia Luccardi, Charles Gertner, Bailey Spry, Daniel Zovatto, Leisa Pulido, Don Hails, and Ele Bardha.

Rotten Tomatoes ranked this film as the sixth most praised film of 2015.

A precursor to the smartphone - the flip-phone of the early & mid 2000's was nicknamed the "clam-shell".

(At around 49:00) There are some high school campus announcements. One is in reference to wrestlers handing forms in to Mr. Dwiggins. This is a nod to the sound editor/re-recording mixer Christian Dwiggins.

This film share a few similarities with another supernatural horror film hit, Stephen King's It (2017). Both movies deal with a shapeshifting demonic entity that relentlessly terrorize a group of youths, the uncomfortable sexual undertones and implications in the narratives, the childlike qualities reflected from the main characters, the sense of dread and uncertainty in the atmosphere due to a dark force, and the groups fighting back against the supernatural threat. And, of course, both films have the word "it" in their titles.

The movie was filmed in Michigan. Jay and Kelly's house is on Trafalgar Way in Sterling Heights. The ice cream parlor where Kelly and Paul work is Clark's Ice Cream in Berkley.

On the Rotten Tomatoes Top 100 Horror Movies list, this film is ranked among the best-rated horror films. Other films include Halloween (1978), Freaks (1932), The Texas Chainsaw Massacre (1974), Misery (1990), Gremlins (1984), Drag Me to Hell (2009), Get Out (2017), The Phantom of the Opera (1925), What Ever Happened to Baby Jane? (1962), Psycho (1960), The Silence of the Lambs (1991), Re-Animator (1985), The Omen (1976), Nosferatu (1922), Near Dark (1987), The Witch (2016), Dracula (1931), The Innocents (1961), Bride of Frankenstein (1935), 28 Days Later... (2002), It Comes at Night (2017), Cat People (1942), Dawn of the Dead (1978), The Babadook (2014), Don't Look Now (1973), The Blair Witch Project (1999), Raw (2017), 28 Days Later... (2002), Das Cabinet des Dr. Caligari (1920), Re-Animator (1985), A Nightmare on Elm Street (1984), Aliens (1986), Suspiria (1977), It Comes at Night (2017), Bride of Frankenstein (1935), Rosemary's Baby (1968), Let the Right One In (2008), Cat People (1942), and Pan's Labyrinth (2006).

Though it doesn't exactly specify which town, the film takes place in the state of Michigan. Principally, some parts were filmed in Detroit judging by some of the landmarks and streets shown in some scenes. However, judging by the college that Jay goes to, which is Oakland University, the story's location is either in Auburn Hills, Michigan or Rochester Hills, Michigan.

Disasterpeace: composer of the soundtrack; plays the announcer in the high school where Jay is searching for Hugh.

Mike Lanier, who plays the very tall "It", is a 7'7" Detroit resident who designs engines for General Motors and is one half of the world's tallest twins.

The colors of red or pink are used to foreshadow the upcoming appearance of It as they appear either in the background or on a character's piece of clothing whenever it attacks.

The director (David Robert Mitchell) said that neither a condom nor same-gender sex would stop the monster and the curse would still be passed.

In the beginning of the film, when the main character Jay is seen looking into the mirror as she gets ready for her date with Hugh, there are two photos on the mirror: one of Jay in the swimming pool and the other of her and her father. At the end of the film, "It" takes the form of her father and attacks Jay in the swimming pool. We also see him in a photo towards the end of the movie.

A ball seems to follow the curse throughout the entire movie and soon after Jay gets infected, a ball hits her window and lands in her garden. When they go to Hugh's house they find a picture of him holding a ball. After Jay has slept with Greg a ball is seen bouncing from the direction of Jay's house towards Greg's house. Finally when Jay sees Greg dying, the motif on her T-shirt, a blonde girl and a ball, is seen clearly. The ball is covered by her hair up until the very moment he dies. She is still wearing the T-shirt later when Paul tries to kiss her implying that she did not go through with her plan to pass it on to the guys on the boat.

Early in the film when Jay's friends are watching a movie on the old TV you can hear the following lines from the movie loud and clear: "You're afraid of an overload. You can't tap enough electricity wherever you get it from to control a strong enough charge". Later in the film when Jay's friends plan to electrocute "It" in the pool, it turns out that they can't tap enough electricity to get a strong enough charge, and the plan fails.

Jay's friends play "Old Maid" when she returns from her date with Hugh. The rules of that game are very similar to the rules of "IT" i.e. you have to pass something on in order not to lose. Moreover most of the specific cards being shown hold strong similarities to characters and events that are not seen until later in the movie. Thus the following cards are shown: "Cranky Kluck" (angry teacher), "Old Maid" (old lady), "Winnie Waite" (waitress), "Bikey Bess" (girl on bike) and "Bronco Buster" (cowboy with guns).

Although the entire movie seems to be reminiscent of the '60s - '80s with no modern technology, Yara is seen several times with a shell-looking touch screen. It looks like a compact mirror, but we see she's reading something from it. Also Annie, the girl in the opening scene is shown calling her father on her mobile phone when she is sitting on the beach.

The final scenes of It Follows (2014) contain several allusions to death and the souls of the dead or ghosts as they are commonly known. In the hospital, Yara reads the following line from The Idiot, "Your soul will leave your body and you will no longer be a person." In the next scene, when Jay and Paul walk down the street, the neighborhood is decorated with fake cobwebs and pumpkins, indicating that the scene takes place around Halloween. Halloween can be traced back to ancient traditions set to honor the souls of the dead. Jay is wearing a white dress and Paul is wearing a long white hoodie, both of them bearing a slight resemblance to popular depictions of ghosts. A "Dead end" sign is seen both in front of them and to their right. The man next to them is busy removing dead leaves. What can be seen of the inscription on Jay's cast reads, "Here lie the bones of Jay."

When Jay's friends play "Old Maid" (the card game played on the porch), there is a slow zoom in on a card that has a cartoon of an old lady on it. This foreshadows the next scene when Jay first sees "It" follow her in the form of an old lady.

The paddling pool in Jay's garden is depicted as a pleasant and safe place and the kids have several pleasant memories from their childhood involving water. In the present however, "bigger pools of water" like lakes, oceans and public swimming pools all seem to be associated with danger and "It". The first girl is killed on the shore of a lake. Jay and Hugh are sitting on the shore of a lake just before he passes the curse on to her. In the classroom, just prior to the appearance of the Old Maid, the camera pans across the cardboard where the text "required reading, The Old man and the sea" is written. Later, when Jay faces the peeing woman in the kitchen, three paintings are seen just before the attack - the first one, depicting a roaring ocean, is seen when Jay is talking to Paul on the couch, and the other two, both depicting lakes, are seen as she walks into the kitchen. In the same scene, the movie playing on the old TV shows a blonde woman in the ocean being attacked by a monster. The subsequent attack by the small boy takes place in the beach cabin near the shores of a lake and the final attack by Jay's father takes place in a big public swimming pool.

The "Its" seen by Jay are mostly wearing white (specifically pajamas, night gowns or undergarments) or are nude.

Someone (or something) in the distance appears to still be following during the final scene of the film.

When Jay and her friends talk to Hugh, Jay is seen carefully placing 5 leaves of grass on her thigh. Later when Jay inspects herself after IT has grabbed her under the water in the public pool, she finds exactly 5 marks on her leg.

Body Count: 2.

The tallest form of It/The Entity(Mike Lanier) shows up twice in the film. The first time is when Jay sees It walking up behind Yara in the doorway to her room. The second time is when she sees it in the rear-view mirror as she drives away from Greg's house after he's killed by The Entity, which was in the form of his mother before switching back to the tall man when it went back to chasing Jay.