This simultaneous provision of meaning in two different languages, one in oral and the other in written text, is thus a new form of language transfer created by film and further developed by television. It combines the two ancient forms of interlingual communication: "interpretation," involving speaking only, and "translation," involving writing only. The concept is sometimes used synonymously with "captioning." In terms of technical production and display on the screen, there is no difference between the two. although it is useful to reserve the term "caption" for the screen display of writing in the same language as the oral text.

     Subtitling is, together with dubbing, the main form of translation or "language transfer" in television, which is increasingly developing into a global medium in a world fragmented by about 5,000 languages. The scope of language-transfer activity depends on the relative power of the television market of each country; its culture, linguistic, and communication environment; and audience preferences. For example, compared to North America. the countries of the European Union have a larger population, more TV viewers, more TV households, and more program production. However, linguistic fragmentation has undermined these countries' ability to perform effectively in the global market or compete with the powerful, monolingual audiovisual economy of the United States. As a step toward the building of a "European single market," the Council of European Communities took measures in 1990 to overcome the "language barrier" by, among other means, promoting dubbing, subtitling, and multilingual broadcasting. The deregulated market of eastern Europe, too, is linguistically fragmented and heavily dependent on imports, with the annual total of foreign programs broadcast in eastern Europe estimated to be 19,000 hours in 1992. English has emerged as the largest source language in the world. Many countries prefer to import programs from the Anglophone audiovisual market in part because it is more economical to conduct language transfer from a single source language.

     The ideal in subtitling is to translate each utterance in full and display it synchronically with the spoken words on the screen. However, the medium imposes serious constraints on full-text translation. One major obstacle involves the limitations of the screen space. Each line, recorded on videotape, consists of approxi­mately 40 characters or typographic spaces (letters, punctuation marks, numbers, and word spaces) in the Roman alphabet, although proportional spacing (e.g., more space for "M" and less for "I") allows more room for words, which average five letters in English. Another constraint is the duration of a subtitle, which depends on the quantity and complexity of the text, the speed of the dialogue, the average viewer's reading speed (150-180 words per minute), and the necessary intervals between subtitles. Taking into account various factors, the optimum display time has been estimated to be four seconds for one line and six to eight seconds for two lines. As a result, the subtitler often presents the source-language dialogue or narration in condensed form. Loss or change of meaning also happens because the written text cannot transfer all the nuances of the spoken language. Other problems relate to the reception process. Unlike the printed page, the changing screen does not allow the viewer to reread a line, which disappears in a few seconds. Audiences have to divide the viewing time between two different activities, reading the subtitles and watching the moving picture, and constantly interrelating the two kinds of text. Thus, subtitling has created not only a new form of translation but also new reading processes and reading audiences. This type of reading demands different literacy skills, which are individually and, often, effectively acquired in the process of viewing.

     Despite the limitations of subtitling, selectively outlined here, some broadcasters and viewers prefer it to dubbing insofar as it does not interfere with the source language. Although viewers of subtitled programs are not usually familiar with the source language, it is argued that they derive more authentic meaning by hearing the original speech.  Preference for one or the other form of language transfer depends on the cultural, political, linguistic, and viewing traditions of each country as well as economic considerations, such as audiovisual market size,  import policies, and the relative cost of each transfer method. It is known, for example, that Europe is divided into "subtitling countries" (e.g., Belgium, Cyprus, Finland, Greece, the Netherlands, Portugal, and Scandinavia) and "dubbing countries" (France, Germany, Italy, and Spain). Dubbing is usually more expensive, more complex, and more time consuming than subtitling or voice-over. Still, some of the economically troubled countries of eastern Europe (Bulgaria, the Czech Republic, Hungary, and Slovakia) dubbed the majority of their imported programs in 1992. In these countries, as in others, the professional community of actors supports the dubbing process as a source of em­ployment.

  Language transfer involves more than facilitating the viewer's comprehension of unfamiliar language. For example, the European Commission has recommended subtitling as a means of improving knowledge of foreign languages within the European Union. Technological innovations are rapidly changing the production, delivery, and reception of subtitles. Some satellite broadcasters provide multilingual subtitling by using a teletext-based system, which allows the simultaneous transmission of up to seven sets of subtitles in different languages. The viewer can choose any language by dialing the assigned teletext page. Subtitling has usually been a post production activity, but real-time subtitling for live broadcasting is available. An interpreter watches a live broadcast and provides simultaneous translation (interpretation) by speaking into a microphone connected to the headphone of a high-speed "audio typist." The interpreted text appears on the screen while it is keyed on the adapted keyboard of a computer programmed for formatting and boxing subtitles. This kind of heavily mediated subtitling will no doubt be simplified when technological advancements in voice recognition allow the direct transcription of the interpreted text. By the early 2000s, the demand for subtitling was growing, especially in Europe, Asia, and Africa; digital broadcasting is expected to revolutionize audiovisual translation by, among other things, facilitating live subtitling; at the same time, a variety of software systems already allows more efficient production of subtitles.