Subtitle
Subtitles are on-screen text most commonly used for translation purposes, but also frequently for text commentaries. In Star Trek, subtitles have often been used to translate alien languages into the viewer's language. Subtitles have also been used in DVD and Blu-ray Disc releases, on several occasions also – but not always – for the audio commentaries when included.

Examples of in-universe languages which have involved subtitles are:

Vulcan (; ; ; )
Klingonese (; ; ; ; ; ; , , , )
The language of the Rubber Tree People ()
Denobulan ()
Xindi-Aquatic (, et al.)
Xindi-Insectoid (, et al.)
 Romulan ()
 Beluga whale speak ()

There was some deliberation over whether a line of Russian that Chekov speaks in  would be accompanied by a subtitle, though it ultimately wasn't. (, issue 91, p. 40)

Gallery of subtitles

Real-world use of subtitles
In many of the larger foreign language areas, such as the locations where the national language is German, French, Spanish or Italian, the dialogue soundtrack of non-native television or film broadcasts, including the (predominantly) English-language Star Trek, are traditionally replaced with a separately recorded dialogue track with local voice-actors, recorded in the respective language for airing in these regions, a process called "dubbing". Nevertheless, in smaller language areas such as Dutch-speaking Europe, the Scandinavian countries and Portugal (though not Brazil where dubbing is commonplace), it is tradition to maintain the original dialogue track, and have them subtitled in the native language – even though dubbing is utilized for television programs aimed at the very young, such as for example the in Dutch dubbed version of  which debuted in April 2022 on Nickelodeon (Netherlands). Dubbing was perpetuated for the older home video format releases such as VHS, but from the LaserDisc optical disc format onward, the original dialogue tracks have been retained, with the option embedded to activate the native-language subtitles and/or, in the above-mentioned cases, a dubbed dialogue track.

English-language optical disc home video format releases usually contain at the very least an English-language subtitle option for the deaf and hard-of-hearing (SDH) as well.

See also
 Text commentary
 Starfleet Access
 Caption

External link
 

Production