Forced subtitles (Ukrainian: форсовані субтитри) are subtitles that appear on the screen regardless of whether subtitles are selected in the player settings. They are used in cases where part of the dialogue in a movie or series is presented in a language different from the main language of the content, and the viewer needs to understand that fragment.
For example, if characters in a movie shot in English speak French during a short scene, forced subtitles provide a translation of that dialogue for viewers. These subtitles are automatically activated and do not depend on the choice of subtitles in the settings menu.
Examples of forced subtitles
To better explain the necessity of forced subtitles, it is probably worth mentioning fictional languages.
"The Lord of the Rings" — subtitles for the language of elves (Sindarin or Quenya). When elves communicate with each other or read ancient inscriptions, these moments are translated using forced subtitles so that viewers can understand what is happening.
"Avatar" — the language of Na'vi. In scenes where the inhabitants of the planet Pandora, the Na'vi, communicate with each other in their language, forced subtitles are used.
"Star Wars" — the language of Huttese, spoken by Jabba the Hutt and other characters. When Jabba or other alien characters speak their fictional languages, subtitles appear on the screen.
"Star Trek" — the language of Klingons. When Klingons communicate in their native language, scenes are accompanied by forced subtitles that translate their phrases.
"Guardians of the Galaxy" — the language of Groot. When Groot says his famous "I am Groot," forced subtitles are usually not used, as viewers understand him without translation, but in certain situations, such as in cartoons or comics, comedic subtitles may be used.
From the latest I saw, it's Dune. In the movie "Dune", forced subtitles are used for fictional languages. And there are several of them:
The language of the Fremen — this is a fictional language of the people who live on the planet Arrakis. When the Fremen communicate in their language, forced subtitles are used in the film so that viewers can understand what is being said.
Bene Gesserit spells — the language used by the members of the Bene Gesserit order for their rituals and training. Forced subtitles explain these moments, giving meaning to the scenes.
The language of the Sardaukar — the Sardaukar are elite soldiers of the emperor. Their fictional language is also accompanied by forced subtitles.