However, most films using sex are only simulating the act. This is for a lot of obvious reasons, but there are some films who throw those reasons out the window and have actors who are down to do the act on film.
And we're not talking about pornographic films either. These movies are well-produced Hollywood films or tasteful art-house projects.
Whether its the film's stars or body double stand-ins, these films all feature actual, unsimulated sex on camera.
Scroll through for the full list.
This 1969 film was directed by Andy Warhol and was the first film featuring explicit sex to get a wide-release in the U.S.
As you might expect from a movie with Warhol's name on it, Blue Movie is experimental. It solely revolves around two lovers in a New York City apartment discussing the Vietnam movie and having unsimulated sex.
Warhol has said the film was around how we should all focus on love instead of war, which is and interesting way to justify filming a ton of sex scenes.
This classic biopic about the titular Roman emperor stars Malcolm McDowell and Helen Mirren, but they don't engage in the sex scenes. Instead, Penthouse Pets were cast for the film's group sex scenes, which are unsimulated.
The Penthouse connection happened because Bob Guccione, the magazine's founder, was a producer. He actually stepped in to film the explicit scenes when director Tinto Brass refused to take part in it.
Lars Von Trier's film's are notorious for their challenging imagery and explicit nature. Three of his films in particular stand out for their use of unsimulated sex during filming.
In The Idiots, there's an orgy that features penetration. In Antichrist, Williem Dafoe and Charlotte Gainsbourg go on an insane journey of loss that ends with a graphic rape and genital mutilation scene. The two actors don't participate in the unsimulated scenes, but body doubles do (minus the mutilation).
There's also sex in Nymphomaniac, as you might expect form its title. Some might think actors like Shia LaBeouf actually participated in the scenes, but they'd be wrong. Starring actors simulated sex, then porn stars came in as body doubles and had real sex on camera. Actors' faces were then CGI-ed onto the porn stars, making it seem like they actually participated.
The Brown Bunny
This controversial film is on this list for one big scene. After a journey to find himself, the male lead (Vincent Gallo) reunites with his ex lover (Chloë Sevigny). She then performs oral sex on him, which is unsimulated.
This 2004 film intertwines musical moments and explicit sex scenes. Actors Kieran O'Brien and Margo Stilley engage in authentic sex through the film, which includes penetration, oral sex and even on-camera ejaculation.
It Is Fine! Everything Is Fine.
Lie With Me
Kissing On The Mouth
The Principles of Lust
Story of the Eye
The Center of the World
James Joyce's Women
You're Driving Me Crazy
Come Play With Me
Reliving Amy Schumer's Sex Scene With John Cena: His Body Is 'Not Even Human'
Sienna Miller Just Revealed All the Steamy Sex Scene Details From Ben Affleck's 'Live by Night'
Stephen King's 'It' Movie Likely Leaving out Book's Most Controversial Sex Scene