Pornography
Pornography is any explicit depiction of sexual acts (images, videos, texts, sounds) produced to arouse whoever is watching it.
Pornography is the explicit depiction of sex, made to arouse. The word comes from the Greek pornē (prostitute) and graphein (to write), and in the 19th century it referred to writing about prostitution. It drifted towards its current meaning with the arrival of photography, then cinema, videotape and finally the internet.
In everyday speech, people say porn, or X-rated, after the X rating that keeps pornographic films away from minors. The line between it and erotica comes down to how much is shown: erotica suggests, plays with what's off-screen and with desire, while pornography shows the genitals and the acts with nothing cut away. That line remains largely subjective and varies across eras and cultures.
As for how it's used, porn mainly serves as fuel for arousal, solo for masturbation, or as a couple as foreplay or a way into talking about fantasies. Watched together, it calls for a bit of negotiation: what turns one of you on can cool the other down, and saying so in advance saves the evening. Nobody is obliged to like it, either, or to watch it in order to have a fulfilling sex life.
The thing to keep in mind is that porn is not a documentary. The bodies are cast, the scenes edited, the durations unrealistic, the roles often heavily stereotyped: taking it as a technical manual or a yardstick of normality is a sure way to build pressure and hang-ups about size, stamina, moaning or looks. A film tells you nothing about what your partner really likes, only talking does.
When watching takes over (it eats into sleep, work or desire for your partner, or comes with difficulty feeling pleasure any other way), it's worth talking to a doctor or a sex therapist rather than feeling guilty on your own.
NB: pornography is a legally regulated industry. Making it requires performers who are adults and consenting, and it may not be shown to minors. Neighbouring terms include erotica, XXX, so-called ethical or feminist porn (which calls for better working conditions on set and a gaze less centred on male performance), and erotic audio, very much in vogue, which leaves the imagination to do the work.
Synonyms : porn, XXX, adult films, X-rated cinema
