Universal translator
The universal translator (also referred to as a "UT" or translator circuit) was a technology used to decipher and interpret alien languages into the native language of the user. (; )

History

On Earth, the universal translator was invented shortly before 2151, and was still experimental at the time of the launch of . () The actual universal translator, which was used for deciphering unknown languages on the fly, was a handheld device with a keypad and display to which a communicator could attach at the top. () 

Despite its being able to translate alien languages in relatively short order, due to the UT's experimental nature, the use of a skilled linguist – in Enterprises case, Hoshi Sato – was still required, notably in situations where reading alien languages on the control panels, hatches, and displays were involved. () 

A new language could quickly be translated in person-to-person encounters by having one speak his or her language until the universal translator gathered enough data to build a translation matrix. Sato also created the linguacode translation matrix in order to anticipate and speed up the translation of new and unknown languages. ()

Without the attachment, Starfleet communicators were still capable of translating preprogrammed languages, such as Akaali when Enterprise visited their world. () By 2155, Ensign Sato's work on universal translator technology had made it possible for small translators to be clipped onto clothing, translating a variety of languages at once, allowing the conference discussing the Coalition of Planets to occur live in real time, without in-person or networked translators among delegates. ()

By the 2230s, universal translators were fully incorporated directly into Starfleet communicators, directing translated audio at the recipient in the speaker's voice. When Lieutenant Philippa Georgiou made first contact with Saru, a Kelpien, she displayed her communicator - making it possible for the two to understand each other. ()

In 2256, Michael Burnham used the universal translator in her communicator aboard the Klingon Sarcophagus ship to eavesdrop on the orders of its commander, . When she revealed herself using the translator to speak in Klingonese, Kol dismissed the technology as another attempt by the Federation to subsume the Klingon identity; Burnham instead explained that its purpose was to enable communication and allow the two species to come to peaceful terms. ()

Starbase Yorktown had a universal translator in the command center that was used to interpret Kalara's plea for help in 2263 of the alternate reality. ()

In 2257, Burnham explained to Siranna that the universal translator in her communicator was programmed with more than 1,000 languages, including the Kelpien language. ()

Universal translators were also built into the communications systems of most starships, including shuttlecraft. In 2257, the universal translator onboard the  still had occasional difficulty with translating the  Linus's language in to Federation Standard. A short time later, communications from a mysterious sphere caused the UT to malfunction, causing the individual crew members and ship's computer to be heard in a large number of languages and for the ship's displays to switch to a wide variety of written languages. These included Klingon, Arabic, German, Welsh, Spanish, French, Italian, Norwegian, Andorian and Tau Cetian. Owing to his language abilities, Commander Saru was able to affect repairs on the UT so the crew could understand each other and the ship's systems again. ()

In 2267, the UT from a Class F shuttlecraft had a wand-like design. ()

In 2267, Captain Kirk and Commander Spock of the  modified one to communicate with an alien known as the Companion, in the Gamma Canaris region. Responding to Zefram Cochrane's question about the theory of operation, Kirk explained that there were certain universal ideas and concepts common to all intelligent life, and that the translator compared the frequencies of brain wave patterns, selected those ideas it recognized, and provided the necessary grammar. Kirk further explained that the device spoke with a voice, or the approximation of one, that corresponded to the identity concepts it recognized. The Companion was revealed to be female because the universal translator detected this facet of its identity from its brain wave patterns, and assigned it a female voice. ()

By the 24th century, universal translators had advanced to the point where a full-fledged UT could be built into the combadges worn by Starfleet personnel. ()

The universal translator was able to translate a language used by sentient nanites into binary language. ()

The Emergency Medical Holographic program contained the universal translator technology built-in to his program. The 's EMH was able to communicate with Noss when Tuvok and Tom Paris' universal translators were offline. ()

In 3190, Dr. Kovich brought a variety of historic universal translators to the DMA task force charged with seeking to establish successful communication with Unknown Species 10-C. The table included 2150s-style communicator with attachment and 2155-style lapel clip-on, a mid-23rd century communicator and two mid-23rd century wand-style translators, and combadges from the 2360s, 2370s, and 2390s. Kovich used them to illustrate that the universal translator had been so successful because it sought out shared familiar concepts between speakers, such as spoken language. ()

Limitations

Non-humanoids 
The universal translator's capabilities were focused on interpreting the brain patterns of humanoid lifeforms. 

For entirely non-humanoid lifeforms, such as a cytoplasmic lifeform which attached itself to B'Elanna Torres, the universal translator was completely stymied, though with some, such as a symbiotic lifeform encountered by  in 2152, it could still provide some help. (; )

At one time while Neelix was negotiating with a xenon-based lifeform, the UT went off-line and Arturis saved him from embarrassment by translating the alien's words. ()

Detection 

The universal translator could be detected when it was used to process language in communications. 

In 2293, Commanders Chekov and Uhura were forced to revert to manually translating their speech using a paper dictionary into Klingon in order to surreptitiously get them past the border. Uhura successfully used broken Klingonese to describe the  as a freighter, the Ursva, headed to Rura Penthe to deliver "supplies, medicines and things". Chekov stated that paper dictionaries were necessary because the use of universal translator would have been recognized. ()

Language structures 
The universal translator was not instantly successful with every language it encountered. 

Even by the late 24th century, it was only capable of translating the literal words of the Tamarians into English, but was unable to translate the Tamarians' metaphorical manner of speaking into understandable speech. (; )

It took several hours of analysis before the universal translator aboard Deep Space 9 could establish a translation matrix for the Skrreean language. ()

When a recording of a Dominion-Federation negotiation was played in native-language mode,  had found the translator missed capturing a passive voice transitive-nuance in Dominionese, revealing what had been translated as a statement was actually a request. ()

Cardassian universal translators had to be manually adjusted in order to properly translate the Breen language. ()

Environmental factors 

Ferengi translators started out as hand-held devices in the 22nd century. () By the 24th century, they had become small devices inserted into the ear. These later models could be were easily disrupted by various types of interferences such as solar flares, ionic interference, or beta radiation. They could potentially be fixed by a Ferengi smacking their head, as Quark, Rom and Nog attempted to do upon their arrival to 2. They contained reset buttons that could be accessed by something small, such as a hairpins. ()

Appendices

See also 
 Linguacode
 Linguistic database
 Recording-translating device
 Translation algorithm
 Translation matrix

Background information 
The universal translator is one of many Star Trek technologies that exist primarily as conventions to aid storytelling. The UT enables the vast majority of dialogue between characters to be written (and delivered) in English, to the convenience of viewers and writers alike. Writers do not have to devise a new language for each new alien of the week that speaks on-screen, and viewers do not have to watch for subtitles.

Another storytelling conceit is that the device makes non-English speakers appear as if they're speaking English (i.e. lip movements match English language pronunciation). This "convention" is particularly obvious in episodes like  as well as , and , in each of which the universal translator is off-line for periods of time. Were the device real, it would more likely have an effect similar to watching a movie dubbed into another language.

The draft proposal Star Trek is... mentioned this concept:
We establish a "telecommunicator" device early in the series, little more complicated than a small transistor radio carried in a pocket. A simple "two-way scrambler", it appears to be converting all spoken language into English. (Roddenberry 11)

During the writing of  (the first regular installment of Star Trek, following the pilot episodes  and ), the universal translator underwent some further development. Jerry Sohl, the writer of "The Corbomite Maneuver", later explained, "We were originally going to have [each crew member] carry a language translator, which would fit on the wrist like a beeper, and no matter what area of the universe they were in, the thoughts that the people were thinking would automatically be translated into English as they spoke. We got rid of that idea, and assumed that everybody did speak English." (The Star Trek Interview Book, pp. 127-128)

External links 
 
 

de:Universalübersetzer
fr:Traducteur universel
it:Traduttore universale
ja:宇宙翻訳機
Communications technology
Linguistics