In the film industry, it is the presentation of sexual activity in a film. In this, the actors engage in an actual sex scene and are not just simulating the actions. This makes the movie a Sexy sex film. At some point in time earlier in the history of film making such scenes were restricted by law and self-imposed industry.
Those films that show explicit sexual activity were confined to privately distribute underground films. Such films were considered in the category of stag films.
Beginning in the late 1960s, mainstream movies began pushing boundaries and started presenting real sex scenes in the film.
Although the vast majority of sexual situations depicted in mainstream cinema is simulated but on rare occasion, actors engage in real sex
The difference between these films and porn movies is that such scenes in a film might be considered arousing and erotic but the intent of these films is not solely pornographic. There can be movies that show real sex scenes but due to its mainstream intent, these are different from pornography.
Sex scenes in movies have been the topic of hot debate for years across the world. May it be western civilization or eastern conservative societies, all have recognized it.
It is a widely accepted notion that western countries had a broader and more modern outlook towards sexual scenes in a movie that eastern part of the world. Therefore it can be said that whether simulated or unsimulated sex scenes permissibly is entirely depended on the region of the world where your target audience lives. Sex scenes are even considered taboo in some countries in the world.